Investments - Schedule of Available-for-sale and Held-to-Maturity Securities Reconciliation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 181,166	$ 65,679
Gross Unrealized Gains	973	16
Gross Unrealized Losses	(200)	(1,761)
Fair Value	181,939	63,934
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,115,323	733,279
Gross Unrealized Gains	21,548	1,487
Gross Unrealized Losses	(1,554)	(13,397)
Fair Value	1,135,317	721,369
Corporate Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	123,116
Gross Unrealized Gains	128
Gross Unrealized Losses	(200)
Fair Value	123,044
Obligations of U.S. Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,954	99,926
Gross Unrealized Gains	92	0
Gross Unrealized Losses	0	(1,428)
Fair Value	10,046	98,498
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	11,704	12,506
Gross Unrealized Gains	170	16
Gross Unrealized Losses	0	(114)
Fair Value	11,874	12,408
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	207,269	26,566
Gross Unrealized Gains	6,118	327
Gross Unrealized Losses	(363)	(83)
Fair Value	213,024	26,810
Residential mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	46,346	53,173
Gross Unrealized Gains	675	0
Gross Unrealized Losses	0	(1,647)
Fair Value	47,021	51,526
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	888,129	596,825
Gross Unrealized Gains	15,083	1,160
Gross Unrealized Losses	(1,191)	(11,849)
Fair Value	902,021	586,136
US Treasury Bill Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,971	9,962
Gross Unrealized Gains	255	0
Gross Unrealized Losses	0	(37)
Fair Value	$ 10,226	$ 9,925