Investments Investment Securities in Unrealized Loss Position (Details) $ in Thousands	Jun. 30, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Fair Value
Less than 12 months	$ 7,848	$ 27,863
12 months or longer	448,060	800,914
Total	455,908	828,777
Unrealized Losses
Less than 12 months	(12)	(139)
12 months or longer	(5,387)	(27,007)
Less than 12 months	$ (5,399)	$ (27,146)
Number of securities | security	120,000	232
Fair Value
Less than 12 months	$ 0	$ 0
12 months or longer	45,951	58,695
Total	45,951	58,695
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(577)	(1,845)
Total	$ (577)	$ (1,845)
Number of securities | security	14,000	16
U.S. government and agencies
Fair Value
Less than 12 months	$ 0	$ 0
12 months or longer	9,934	29,114
Total	9,934	29,114
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(114)	(929)
Less than 12 months	$ (114)	$ (929)
Number of securities | security	2,000	5
Government-sponsored entities
Fair Value
Less than 12 months	$ 0	$ 0
12 months or longer	70,069	207,703
Total	70,069	207,703
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(65)	(3,952)
Less than 12 months	$ (65)	$ (3,952)
Number of securities | security	13,000	32
Municipal bonds
Fair Value
Less than 12 months	$ 7,794	$ 25,394
12 months or longer	14,930	130,209
Total	22,724	155,603
Unrealized Losses
Less than 12 months	(12)	(128)
12 months or longer	(80)	(2,973)
Less than 12 months	$ (92)	$ (3,101)
Number of securities | security	16,000	85
Mortgage-backed securities
Fair Value
Less than 12 months	$ 54	$ 2,469
12 months or longer	353,127	433,888
Total	353,181	436,357
Unrealized Losses
Less than 12 months	0	(11)
12 months or longer	(5,128)	(19,153)
Less than 12 months	$ (5,128)	$ (19,164)
Number of securities | security	89,000	110
Fair Value
Less than 12 months	$ 0	$ 0
12 months or longer	45,951	58,695
Total	45,951	58,695
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(577)	(1,845)
Total	$ (577)	$ (1,845)
Number of securities | security	14,000	16