Summary of Significant Accounting Policies and New Accounting Pronouncements - Calculation of Lifetime ECL (Details)	12 Months Ended
	Dec. 31, 2023 scenario
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of forward-looking economic scenarios	4
Reasonable and supportable forecast period for consensus economic scenarios	2 years
Reversion period for average historical values	20 years
Linear basis reversion period	3 years
Consumer loans | Residential mortgages | Minimum
Financing Receivable, Allowance for Credit Loss [Line Items]
Expected loss severity percentage	20.00%
Consumer loans | Residential mortgages | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Expected loss severity percentage	40.00%