Investment Securities (Contractual Maturities of Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Available-for-sale securities
Due in one year or less, amortized cost	$ 49,714	$ 343,601
Due in one to five years, amortized cost	72,382	67,901
Due in five to ten years, amortized cost	118,358	111,886
Due after ten years, amortized cost	69,200	95,672
Amortized Cost	2,316,369	2,960,081
Due in one to five years, fair value	49,822	343,846
Due in five to ten years, fair value	73,850	70,334
Due after ten years, fair value	117,573	112,178
Mortgage-backed, without single maturity date, fair value	72,560	101,441
Fair Value	2,327,793	3,055,839
Held-to-maturity securities
Held-to-maturity securities, due in one year or less, amortized cost	2,976	7,138
Held-to-maturity securities, due in one to five years, amortized cost	79,422	22,217
Held-to-maturity securities, due in five to ten years, amortized cost	106,713	150,621
Held-to-maturity securities, due after ten years, amortized cost	222,522	198,690
Amortized Cost	2,942,363	579,197
Less: Allowance for credit losses	(78)	(59)
Held-to-maturity securities, net of allowance for credit losses	2,942,285	579,138
Held-to-maturity securities, due in one year or less, fair value	2,992	7,186
Held-to-maturity securities, due in one to five years, fair value	79,705	23,068
Held-to-maturity securities, due in five to ten years, fair value	112,667	159,293
Held-to-maturity securities, due after ten years, fair value	221,358	203,689
Fair Value	2,900,694	593,767
Mortgage-backed
Available-for-sale securities
Mortgage-backed, without single maturity date, amortized cost	2,006,715	2,341,021
Held-to-maturity securities
Mortgage-backed, amortized cost	2,530,730	200,531
Mortgage-backed, fair value	2,483,972	200,531
Mortgage-backed	$ 2,013,988	$ 2,428,040