Short-Term Borrowings - Maturities of Outstanding Advances Under Repurchase Agreements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Mortgage loans sold under agreement to repurchase
Unpaid principal balance	$ 7,297,360
Weighted-average maturity (in months)	2 months 21 days
Within 30 days
Mortgage loans sold under agreement to repurchase
Unpaid principal balance	$ 1,152,623
Over 30 to 90 days
Mortgage loans sold under agreement to repurchase
Unpaid principal balance	5,640,686
Over 90 to 180 days
Mortgage loans sold under agreement to repurchase
Unpaid principal balance	308,434
Over 180 days to one year
Mortgage loans sold under agreement to repurchase
Unpaid principal balance	95,617
Over one year to two year
Mortgage loans sold under agreement to repurchase
Unpaid principal balance	$ 100,000