Securities Available for Sale - Aggregate Unrealized Losses and Fair Value (Details) $ in Thousands	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities, Less than 12 months | security	35	21
Number of Securities, 12 months or longer | security	57	198
Number of Securities, Total | security	92	219
Fair Value - Less than 12 months	$ 269,737	$ 72,036
Fair Value - 12 months or longer	405,841	1,422,127
Fair Value - Total	675,578	1,494,163
Gross Unrealized Losses - Less than 12 months	(2,064)	(366)
Gross Unrealized Losses - 12 months or longer	(5,704)	(49,997)
Gross Unrealized Losses - Total	$ (7,768)	$ (50,363)
Collateralized Mortgage Obligations
Debt Securities, Available-for-sale [Line Items]
Number of Securities, Less than 12 months | security	20	1
Number of Securities, 12 months or longer | security	32	93
Number of Securities, Total | security	52	94
Fair Value - Less than 12 months	$ 108,236	$ 8,041
Fair Value - 12 months or longer	183,050	700,095
Fair Value - Total	291,286	708,136
Gross Unrealized Losses - Less than 12 months	(721)	(28)
Gross Unrealized Losses - 12 months or longer	(1,938)	(21,101)
Gross Unrealized Losses - Total	$ (2,659)	$ (21,129)
Mortgage-backed Securities, Residential
Debt Securities, Available-for-sale [Line Items]
Number of Securities, Less than 12 months | security	6	4
Number of Securities, 12 months or longer | security	16	45
Number of Securities, Total | security	22	49
Fair Value - Less than 12 months	$ 84,107	$ 19,973
Fair Value - 12 months or longer	129,457	363,334
Fair Value - Total	213,564	383,307
Gross Unrealized Losses - Less than 12 months	(267)	(37)
Gross Unrealized Losses - 12 months or longer	(1,331)	(13,064)
Gross Unrealized Losses - Total	$ (1,598)	$ (13,101)
Mortgage-backed Securities, Commercial
Debt Securities, Available-for-sale [Line Items]
Number of Securities, Less than 12 months | security	7	3
Number of Securities, 12 months or longer | security	5	27
Number of Securities, Total | security	12	30
Fair Value - Less than 12 months	$ 68,452	$ 38,494
Fair Value - 12 months or longer	73,697	312,428
Fair Value - Total	142,149	350,922
Gross Unrealized Losses - Less than 12 months	(1,037)	(218)
Gross Unrealized Losses - 12 months or longer	(1,323)	(12,761)
Gross Unrealized Losses - Total	$ (2,360)	$ (12,979)
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Number of Securities, Less than 12 months | security	2	13
Number of Securities, 12 months or longer | security	3	32
Number of Securities, Total | security	5	45
Fair Value - Less than 12 months	$ 8,942	$ 5,528
Fair Value - 12 months or longer	15,437	42,444
Fair Value - Total	24,379	47,972
Gross Unrealized Losses - Less than 12 months	(39)	(83)
Gross Unrealized Losses - 12 months or longer	(312)	(1,897)
Gross Unrealized Losses - Total	$ (351)	$ (1,980)
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Number of Securities, Less than 12 months | security	0	0
Number of Securities, 12 months or longer | security	1	1
Number of Securities, Total | security	1	1
Fair Value - Less than 12 months	$ 0	$ 0
Fair Value - 12 months or longer	4,200	3,826
Fair Value - Total	4,200	3,826
Gross Unrealized Losses - Less than 12 months	0	0
Gross Unrealized Losses - 12 months or longer	(800)	(1,174)
Gross Unrealized Losses - Total	$ (800)	$ (1,174)