v3.26.1
Discontinued operations - Summary of movement schedules by type of liability (Detail) - EUR (€)
€ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance € 176,049  
Closing net balance 137,391 € 176,049
Net opening balance, Investment contracts 21,281 22,332
Insurance revenue (19) (77)
Incurred claims and expenses 6 30
Onerous contract losses (and reversals) (1) 2
Insurance service expenses 6 32
Investment components 0 0
Insurance service result (13) (45)
Insurance finance (income) / expenses (440) 2,916
Cash flows (746) (2,744)
Net exchange differences 133 (1,177)
Net closing balance, Investment contracts 20 21,281
LFRC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 21,278 22,332
Insurance revenue (19) (77)
Incurred claims and expenses 0 0
Onerous contract losses (and reversals) 0 0
Insurance service expenses 0 0
Investment components (838) (3,109)
Insurance service result (857) (3,186)
Insurance finance (income) / expenses (440) 2,916
Cash flows 99 394
Net exchange differences 133 (1,177)
Net closing balance, Investment contracts 20 21,278
LC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 2 0
Insurance revenue 0 0
Incurred claims and expenses 0 0
Onerous contract losses (and reversals) (1) 2
Insurance service expenses (1) 2
Investment components 0 0
Insurance service result (1) 2
Insurance finance (income) / expenses 0 0
Cash flows 0 0
Net exchange differences 0 0
Net closing balance, Investment contracts 0 2
LFIC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 1 0
Insurance revenue 0 0
Incurred claims and expenses 7 30
Onerous contract losses (and reversals) 0 0
Insurance service expenses 7 30
Investment components 838 3,109
Insurance service result 844 3,139
Insurance finance (income) / expenses 0 0
Cash flows (845) (3,138)
Net exchange differences 0 0
Net closing balance, Investment contracts 0 1
Insurance contracts other than those to which premium allocation approach has been applied [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 176,006  
Closing net balance 137,341 176,006
Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 176,006 188,193
Insurance revenue (4,265) (8,906)
Incurred claims and other insurance service expenses 3,370 7,589
Onerous contract losses (and reversals) 888 1,139
Insurance service expenses 4,535 9,267
Investment components 0 0
Insurance service result 270 361
Insurance finance (income) / expenses 5,334 18,143
Cash flows (5,238) (11,326)
Net exchange differences 3,946 (19,358)
Closing net balance 137,341 176,006
Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member] | LFRC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 141,539 157,971
Insurance revenue (4,265) (8,906)
Incurred claims and other insurance service expenses 0 0
Onerous contract losses (and reversals) 0 0
Insurance service expenses 276 538
Investment components (2,106) (5,809)
Insurance service result (6,095) (14,177)
Insurance finance (income) / expenses 5,285 18,005
Cash flows (2,985) (4,721)
Net exchange differences 2,902 (15,522)
Closing net balance 97,710 141,539
Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member] | LFIC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 31,611 27,596
Insurance revenue 0 0
Incurred claims and other insurance service expenses 3,592 7,967
Onerous contract losses (and reversals) 0 0
Insurance service expenses 3,593 7,967
Investment components 2,106 5,809
Insurance service result 5,699 13,776
Insurance finance (income) / expenses 0 0
Cash flows (2,047) (6,252)
Net exchange differences 954 (3,510)
Closing net balance 36,187 31,611
Investment contracts with DPF [member] | Insurance contracts other than those to which premium allocation approach has been applied [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 21,281 22,332
Net closing balance, Investment contracts 20 21,281
Discontinued operations [member] | Insurance contracts issued [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Transfers to disposal groups 42,977  
Discontinued operations [member] | Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 0  
Transfers to disposal groups 42,977  
Insurance revenue (94)  
Incurred claims and other insurance service expenses 35  
Onerous contract losses (and reversals) (4)  
Insurance service expenses 31  
Investment components 0  
Insurance service result (62)  
Insurance finance (income) / expenses 4,390  
Cash flows (777)  
Net exchange differences 330  
Closing net balance 46,857 0
Discontinued operations [member] | Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member] | LFRC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 0  
Transfers to disposal groups 42,936  
Insurance revenue (94)  
Incurred claims and other insurance service expenses 0  
Onerous contract losses (and reversals) 0  
Insurance service expenses 0  
Investment components (1,362)  
Insurance service result (1,456)  
Insurance finance (income) / expenses 4,390  
Cash flows 621  
Net exchange differences 329  
Closing net balance 46,821 0
Discontinued operations [member] | Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member] | LC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 0  
Transfers to disposal groups 11  
Insurance revenue 0  
Incurred claims and other insurance service expenses 0  
Onerous contract losses (and reversals) (4)  
Insurance service expenses (4)  
Investment components 0  
Insurance service result (4)  
Insurance finance (income) / expenses 0  
Cash flows 0  
Net exchange differences 0  
Closing net balance 7 0
Discontinued operations [member] | Insurance contracts issued [member] | Insurance contracts other than those to which premium allocation approach has been applied [member] | LFIC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Opening net balance 0  
Transfers to disposal groups 29  
Insurance revenue 0  
Incurred claims and other insurance service expenses 35  
Onerous contract losses (and reversals) 0  
Insurance service expenses 35  
Investment components 1,362  
Insurance service result 1,397  
Insurance finance (income) / expenses 0  
Cash flows (1,398)  
Net exchange differences 0  
Closing net balance 29 0
Discontinued operations [member] | Investment contracts with DPF [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 0  
Transfers to disposal groups 20,196  
Insurance revenue (21)  
Incurred claims and expenses 6  
Onerous contract losses (and reversals) (1)  
Insurance service expenses 5  
Investment components 0  
Insurance service result (16)  
Insurance finance (income) / expenses 2,110  
Cash flows (666)  
Net exchange differences 153  
Net closing balance, Investment contracts 21,777 0
Discontinued operations [member] | Investment contracts with DPF [member] | LFRC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 0  
Transfers to disposal groups 20,194  
Insurance revenue (21)  
Incurred claims and expenses 0  
Onerous contract losses (and reversals) 0  
Insurance service expenses 0  
Investment components (746)  
Insurance service result (767)  
Insurance finance (income) / expenses 2,110  
Cash flows 86  
Net exchange differences 153  
Net closing balance, Investment contracts 21,776 0
Discontinued operations [member] | Investment contracts with DPF [member] | LC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 0  
Transfers to disposal groups 1  
Insurance revenue 0  
Incurred claims and expenses 0  
Onerous contract losses (and reversals) (1)  
Insurance service expenses (1)  
Investment components 0  
Insurance service result (1)  
Insurance finance (income) / expenses 0  
Cash flows 0  
Net exchange differences 0  
Net closing balance, Investment contracts 0 0
Discontinued operations [member] | Investment contracts with DPF [member] | LFIC [member]    
Disclosure In Tabular Form Of Insurance And Investment Contracts With Discretionary Participating Features [Line Items]    
Net opening balance, Investment contracts 0  
Transfers to disposal groups 0  
Insurance revenue 0  
Incurred claims and expenses 6  
Onerous contract losses (and reversals) 0  
Insurance service expenses 6  
Investment components 746  
Insurance service result 752  
Insurance finance (income) / expenses 0  
Cash flows (752)  
Net exchange differences 0  
Net closing balance, Investment contracts € 0 € 0