Allowance for Credit Losses and Credit Quality of Loans (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Allowance for Credit Losses [Abstract]
Allowance for credit losses	[1]	$ 113,500
Retained earnings		703,322		$ 696,214
ASU 2016-13 [Member]
Allowance for Credit Losses [Abstract]
Allowance for credit losses		113,500	$ 100,000	75,999
AIR on loans		$ 26,800
ASU 2016-13 [Member] | Minimum [Member]
Allowance for Credit Losses [Abstract]
Write-off of uncollectible interest period		120 days
ASU 2016-13 [Member] | Accrued Interest Receivable [Member]
Allowance for Credit Losses [Abstract]
Allowance for credit losses		$ 1,100
ASU 2016-13 [Member] | Cumulative Effect Adjustment for ASU Implementation [Member]
Allowance for Credit Losses [Abstract]
Allowance for credit losses				3,000
Retained earnings				(4,300)
Deferred tax asset				(1,500)
ASU 2016-13 [Member] | Cumulative Effect Adjustment for ASU Implementation [Member] | Loans [Member]
Allowance for Credit Losses [Abstract]
Allowance for credit losses				3,000
Retained earnings				(2,300)
Deferred tax asset				$ 700

[1] Beginning January 1, 2020, calculation is based on current expected loss methodology. Prior to January 1, 2020, calculation was based on incurred loss methodology.