Fair Value Measurements - Quantitative Inputs and Assumptions Used to Determine Fair Value for Private Label CMOs and Asset-backed Securities Available-for-sale (Details) - Level 3 - Asset-backed Securities - Fair Value, Measurements, Recurring	3 Months Ended
	Mar. 31, 2022
Measurement Input, Prepayment Rate | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.150
Measurement Input, Prepayment Rate | Weighted Average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.150	[1]
Measurement Input, Default Rate | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.020
Measurement Input, Default Rate | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.020
Measurement Input, Default Rate | Weighted Average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.020	[1],[2]
Measurement Input, Loss Severity | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.600
Measurement Input, Loss Severity | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.600
Measurement Input, Loss Severity | Weighted Average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.600	[1],[2]
Measurement Input, Discount Rate | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.046
Measurement Input, Discount Rate | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.048
Measurement Input, Discount Rate | Weighted Average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Asset-Backed Securities, Measurement Input	0.048	[1]

[1] iscount rates for private label commercial MBS were weighted by the relative fair values of the instruments.

[2] nnual default rates, and loss severity rates were the same for all of the private label commercial MBS.