Investment Securities (Other-Than-Temporary Impairment) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt securities, available for sale:
Less than twelve months, estimated fair value	$ 107,424	$ 61,213
Less than twelve months, unrealized losses	506	434
Twelve months or longer, estimated fair value	98,175	405,458
Twelve months or longer, unrealized losses	1,262	12,328
Total, fair value	205,599	466,671
Total, unrealized losses	1,768	12,762
Investment securities held-to-maturity
Less than twelve months, estimated fair value	9,902	14,813
Less than twelve months, unrealized losses	52	107
Twelve months or longer, estimated fair value	12,439	87,291
Twelve months or longer, unrealized losses	102	1,871
Total, estimated fair value	22,341	102,104
Total, unrealized losses	154	1,978
Available-for-sale Securities and Held-to-maturity Securities [Abstract] (Deprecated 2018-01-31)
Less Than Twelve Months, Estimated Fair Value	117,326	76,026
Less Than Twelve Months, Unrealized Losses	558	541
Twelve Months or Longer, Estimated Fair Value	110,614	492,749
Twelve Months or Longer, Unrealized Losses	1,364	14,199
Total, Estimated Fair Value	227,940	568,775
Total, Unrealized Losses	1,922	14,740
GSE debentures
Debt securities, available for sale:
Less than twelve months, estimated fair value	10,965	25,780
Less than twelve months, unrealized losses	58	191
Twelve months or longer, estimated fair value	0	130,284
Twelve months or longer, unrealized losses	0	2,901
Total, fair value	10,965	156,064
Total, unrealized losses	58	3,092
Investment securities held-to-maturity
Less than twelve months, estimated fair value	8,714	0
Less than twelve months, unrealized losses	30	0
Twelve months or longer, estimated fair value	2,977	40,653
Twelve months or longer, unrealized losses	21	967
Total, estimated fair value	11,691	40,653
Total, unrealized losses	51	967
GSE CMOs
Debt securities, available for sale:
Less than twelve months, estimated fair value	28,659	0
Less than twelve months, unrealized losses	217	0
Twelve months or longer, estimated fair value	55,885	102,630
Twelve months or longer, unrealized losses	874	4,250
Total, fair value	84,544	102,630
Total, unrealized losses	1,091	4,250
GSE MBSs
Debt securities, available for sale:
Less than twelve months, estimated fair value	42,046	21,487
Less than twelve months, unrealized losses	115	113
Twelve months or longer, estimated fair value	42,257	138,051
Twelve months or longer, unrealized losses	388	4,256
Total, fair value	84,303	159,538
Total, unrealized losses	503	4,369
Investment securities held-to-maturity
Less than twelve months, estimated fair value	0	0
Less than twelve months, unrealized losses	0	0
Twelve months or longer, estimated fair value	9,257	11,080
Twelve months or longer, unrealized losses	81	295
Total, estimated fair value	9,257	11,080
Total, unrealized losses	81	295
SBA commercial loan asset-backed securities
Debt securities, available for sale:
Less than twelve months, estimated fair value	0	0
Less than twelve months, unrealized losses	0	0
Twelve months or longer, estimated fair value	33	51
Twelve months or longer, unrealized losses	0	0
Total, fair value	33	51
Total, unrealized losses	0	0
Corporate debt obligations
Debt securities, available for sale:
Less than twelve months, estimated fair value		10,019
Less than twelve months, unrealized losses		93
Twelve months or longer, estimated fair value		29,689
Twelve months or longer, unrealized losses		817
Total, fair value		39,708
Total, unrealized losses		910
U.S. treasury bonds
Debt securities, available for sale:
Less than twelve months, estimated fair value	25,754	3,927
Less than twelve months, unrealized losses	116	37
Twelve months or longer, estimated fair value	0	4,753
Twelve months or longer, unrealized losses	0	104
Total, fair value	25,754	8,680
Total, unrealized losses	116	141
Municipal obligations
Investment securities held-to-maturity
Less than twelve months, estimated fair value	710	14,813
Less than twelve months, unrealized losses	0	107
Twelve months or longer, estimated fair value	205	35,058
Twelve months or longer, unrealized losses	0	609
Total, estimated fair value	915	49,871
Total, unrealized losses	0	716
Foreign government obligations
Investment securities held-to-maturity
Less than twelve months, estimated fair value	478	0
Less than twelve months, unrealized losses	22	0
Twelve months or longer, estimated fair value	0	500
Twelve months or longer, unrealized losses	0	0
Total, estimated fair value	478	500
Total, unrealized losses	$ 22	$ 0