Investments - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 960,984		$ 1,115,323
Securities available for sale	998,104		$ 1,135,317
accumulated other comprehensive income loss available for sale securities adjustment pre tax	$ 11,500
Maximum percentage of shareholders' equity security holdings held of one issuer	10.00%		10.00%
Securities pledged	$ 449,900		$ 484,800
Mortgage-backed securities, weighted average life	3 years
Accrued interest receivable, available-for-sale securities	$ 3,600
Accrued interest receivable, held-to-maturity securities	2,300
Allowance for credit losses on held-to-maturity debt securities	645	$ 0
Reclassified to Held to Maturity [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	163,600
Securities available for sale	$ 175,100