Advances Advances - Prepayment Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank Advances Prepayment Fees [Abstract]
Prepayment fees received from borrowers	$ 33,809	$ 409	$ 1,568
Hedging fair-value adjustments on prepaid advances	1,923	264	(218)
Net discounts (premiums) associated with prepaid advances	157	(159)	(137)
Deferred recognition of prepayment fees received from borrowers on advance prepayments deemed to be loan modifications	(1,793)	(298)	(315)
Prepayment fees recognized in income on advance restructurings deemed to be extinguishments	915	0	0
Advance prepayment fees recognized in income, net	$ 35,011	$ 216	$ 898