Debt Securities Held to Maturity Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) security	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) security	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) security
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	$ 289,089,000		$ 289,089,000		$ 262,143,000
Fair value	296,325,000		296,325,000		254,841,000
Proceeds from sale of held-to-maturity securities	0		0	$ 0
Proceeds from sale and maturity of held-to-maturity securities	23,400,000	$ 0	28,400,000
Debt securities, held-to-maturity, sold, realized gain (loss)	24,000		24,000
Fair value of securities sold under agreements to repurchase	$ 180,400,000		$ 180,400,000		$ 187,000,000
Number of positions | security	20		20		88
Other-than-temporary impairment loss, held-to-maturity, before tax	$ 0	$ 0	$ 0	$ 0
Mortgage-backed securities and collateralized mortgage obligations
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	264,089,000		264,089,000		$ 238,739,000
Fair value	$ 271,397,000		$ 271,397,000		$ 231,600,000