Changes In Accumulated Other Comprehensive Income (Loss) By Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 956,816	$ 920,964	$ 855,872
Unrealized gains (losses) arising during period, before tax	28,531	(44,074)
Income tax effect	(7,418)	11,460
Other comprehensive income (loss) before reclassifications	21,113	(32,614)
Reclassification adjustments for losses (gains) included in net income, before tax	406	15,742
Income tax effect	(106)	(4,093)
Amounts reclassified from accumulated other comprehensive income (loss) to net income	300	11,649
Net current-period other comprehensive income (loss)	21,413	(20,965)
Ending balance	1,052,795	956,816	920,964
Reclassification, cash flow hedge, before tax	(1,407)	2,917	(2,634)
Unrealized Gains (Losses), available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(21,741)	(249)
Balance after reclassification adjustments				$ (1,458)
Unrealized gains (losses) arising during period, before tax	49,688	(46,069)
Income tax effect	(12,919)	11,978
Other comprehensive income (loss) before reclassifications	36,769	(34,091)
Reclassification adjustments for losses (gains) included in net income, before tax	(1,001)	18,659
Income tax effect	260	(4,851)
Amounts reclassified from accumulated other comprehensive income (loss) to net income	(741)	13,808
Net current-period other comprehensive income (loss)	36,028	(20,283)
Ending balance	14,287	(21,741)	(249)
Foreign Currency Items, available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	0	88
Balance after reclassification adjustments				0
Unrealized gains (losses) arising during period, before tax	0	0
Income tax effect	0	0
Other comprehensive income (loss) before reclassifications	0	0
Reclassification adjustments for losses (gains) included in net income, before tax	0	0
Income tax effect	0	0
Amounts reclassified from accumulated other comprehensive income (loss) to net income	0	0
Net current-period other comprehensive income (loss)	0	0
Ending balance	0	0	88
Total unrealized gains (losses), available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(21,741)	(161)
Balance after reclassification adjustments				(1,458)
Unrealized gains (losses) arising during period, before tax	49,688	(46,069)
Income tax effect	(12,919)	11,978
Other comprehensive income (loss) before reclassifications	36,769	(34,091)
Reclassification adjustments for losses (gains) included in net income, before tax	(1,001)	18,659
Income tax effect	260	(4,851)
Amounts reclassified from accumulated other comprehensive income (loss) to net income	(741)	13,808
Net current-period other comprehensive income (loss)	36,028	(20,283)
Ending balance	14,287	(21,741)	(161)
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(922)	(198)
Balance after reclassification adjustments				(240)
Unrealized gains (losses) arising during period, before tax	(21,157)	1,995
Income tax effect	5,501	(518)
Other comprehensive income (loss) before reclassifications	(15,656)	1,477
Reclassification adjustments for losses (gains) included in net income, before tax	1,407	(2,917)
Income tax effect	(366)	758
Amounts reclassified from accumulated other comprehensive income (loss) to net income	1,041	(2,159)
Net current-period other comprehensive income (loss)	(14,615)	(682)
Ending balance	(15,537)	(922)	(198)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(22,663)	(359)	(4,892)
Balance after reclassification adjustments				(1,698)
Ending balance	$ (1,250)	(22,663)	$ (359)
Non-interest income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassification, cash flow hedge, after tax		70
Reclassification, cash flow hedge, before tax		95
Other non-interest income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassification, cash flow hedge, after tax		2,100
Reclassification, cash flow hedge, before tax		$ 2,800
Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				0
Accounting Standards Update 2018-02 | Unrealized Gains (Losses), available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(256)
Accounting Standards Update 2018-02 | Foreign Currency Items, available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				0
Accounting Standards Update 2018-02 | Total unrealized gains (losses), available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(256)
Accounting Standards Update 2018-02 | Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(42)
Accounting Standards Update 2018-02 | Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(298)
Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				0
Accounting Standards Update 2016-01 | Unrealized Gains (Losses), available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(953)
Accounting Standards Update 2016-01 | Foreign Currency Items, available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(88)
Accounting Standards Update 2016-01 | Total unrealized gains (losses), available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(1,041)
Accounting Standards Update 2016-01 | Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				0
Accounting Standards Update 2016-01 | Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				(1,041)
Combined effect of multiple accounting pronouncements on components of shareholders' equity | Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect adjustment				$ (1,300)