| 
							 17 Deferred tax liabilities (net)  | 
					||||
| 
							 (₹ In Crore)  | 
					||||
| 
							 Particulars  | 
						
							 As at 31 March  | 
					|||
| 
							 2024  | 
						
							 2023  | 
					|||
| 
							 
  | 
						||||
| 
							 Deferred tax liabilities  | 
						||||
| 
							 On account of timing difference in  | 
						||||
| 
							 Property, plant and equipment  | 
						
							 178.56  | 
						
							 149.60  | 
					||
| 
							 
  | 
						||||
| 
							 Employee benefits:  | 
						||||
| 
							 Defined benefit plans provisions – P&L  | 
						
							 10.09  | 
						
							 9.67  | 
					||
| 
							 Defined benefit plans provisions – OCI  | 
						
							 0.42  | 
						
							 0.42  | 
					||
| 
							 
  | 
						||||
| 
							 Financial instruments:  | 
						||||
| 
							 Mutual funds including fixed maturity plans, ETFs  | 
						
							 194.83  | 
						
							 152.30  | 
					||
| 
							 Financial assets at FVTOCI  | 
						
							 210.41  | 
						
							 117.17  | 
					||
| 
							 405.24  | 
						
							 269.47  | 
					|||
| 
							 Gross deferred tax liabilities  | 
						
							 594.31  | 
						
							 429.16  | 
					||
| 
							 Deferred tax assets  | 
						||||
| 
							 On account of timing difference in  | 
						||||
| 
							 Employee benefits:  | 
						||||
| 
							 Welfare scheme costs & others  | 
						
							 0.21  | 
						
							 0.34  | 
					||
| 
							 Bonus provisions  | 
						
							 1.72  | 
						
							 1.72  | 
					||
| 
							 Provision for privilege leave etc.  | 
						
							 37.22  | 
						
							 33.89  | 
					||
| 
							 Defined benefit plans provisions – P&L  | 
						
							 –  | 
						
							 –  | 
					||
| 
							 Defined benefit plans provisions – OCI  | 
						
							 5.28  | 
						
							 14.21  | 
					||
| 
							 44.43  | 
						
							 50.16  | 
					|||
| 
							 Financial instruments:  | 
						||||
| 
							 Amortisation on acquisition/liquidation of fixed income securities  | 
						
							 24.94  | 
						
							 9.86  | 
					||
| 
							 24.94  | 
						
							 9.86  | 
					|||
| 
							 Other items:  | 
						||||
| 
							 Provision for bad/doubtful debts and advances  | 
						
							 5.89  | 
						
							 11.89  | 
					||
| 
							 Taxes, duties, others etc.  | 
						
							 12.11  | 
						
							 12.10  | 
					||
| 
							 18.00  | 
						
							 23.99  | 
					|||
| 
							 Gross deferred tax assets  | 
						
							 87.37  | 
						
							 84.01  | 
					||
| 
							 506.94  | 
						
							 345.15  | 
					|||
| 
							 Movement in deferred tax liabilities (net):  | 
					|||||||||||
| 
							 (₹ In Crore)  | 
					|||||||||||
| 
							 Particulars  | 
						
							 Property, plant and equipment  | 
						
							 Financial instruments  | 
						
							 Employee benefits  | 
						
							 Other items  | 
						
							 Total  | 
					||||||
| 
							 
  | 
						|||||||||||
| 
							 At 31 March 2022  | 
						
							 116.03  | 
						
							 343.32  | 
						
							 (31.90)  | 
						
							 (24.12)  | 
						
							 403.33  | 
					||||||
| 
							 Charged/(credited)  | 
						|||||||||||
| 
							 –  | 
						
							 to profit and loss  | 
						
							 33.57  | 
						
							 (99.86)  | 
						
							 (7.64)  | 
						
							 0.15  | 
						
							 (73.78)  | 
					|||||
| 
							 –  | 
						
							 to other comprehensive income  | 
						
							 –  | 
						
							 16.15  | 
						
							 (0.53)  | 
						
							 (0.02)  | 
						
							 15.60  | 
					|||||
| 
							 At 31 March 2023  | 
						
							 149.60  | 
						
							 259.61  | 
						
							 (40.07)  | 
						
							 (23.99)  | 
						
							 345.15  | 
					||||||
| 
							 Charged/(credited)  | 
						|||||||||||
| 
							 –  | 
						
							 to profit and loss  | 
						
							 28.96  | 
						
							 27.45  | 
						
							 (2.78)  | 
						
							 5.99  | 
						
							 59.62  | 
					|||||
| 
							 –  | 
						
							 to other comprehensive income  | 
						
							 –  | 
						
							 93.24  | 
						
							 8.93  | 
						
							 –  | 
						
							 102.17  | 
					|||||
| 
							 At 31 March 2024  | 
						
							 178.56  | 
						
							 380.30  | 
						
							 (33.92)  | 
						
							 (18.00)  | 
						
							 506.94  | 
					||||||
