Shareholders' Equity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares	Feb. 28, 2021 shares	Jan. 31, 2020 shares	Jan. 31, 2019 shares	Dec. 31, 2015 USD ($)	Oct. 08, 2015 USD ($)
Total risk-based capital:
Actual Regulatory Capital - Amount	$ 498,290	$ 455,702
Capital To Risk Weighted Assets	0.1540	0.1444
Minimum Requirement for capital Adequacy Including Capital Buffer Total Risk-Based Capital Ratio	10.50%
Minimum Regulatory Capital Required - Ratio		0.1050
Minimum Regulatory Provision To Be Well Capitalized - Ratio	0.1000	0.1000
Tier 1 capital:
Actual Regulatory Capital - Amount	$ 445,858	$ 415,511
Actual Regulatory Capital - Ratio	0.1378	0.1316
Minimum Requirement for capital Adequacy Including Capital Buffer Tier I Risk-Based Capital Ratio	8.50%
Minimum Regulatory Capital Required - Ratio		0.0850
Minimum Regulatory Provision To Be Well Capitalized - Ratio	0.0600	0.0600
Common equity tier I capital	$ 402,858	$ 372,511
Tier 1 leverage capital ratio:
Actual Regulatory Capital - Amount	$ 445,858	$ 415,511
Actual Regulatory Capital - Ratio	0.0913	0.0955
Minimum Regulatory Capital Required - Ratio	0.0400	0.0400
Common Equity Tier I Risk Based Capital Ratio	12.45%	11.80%
Minimum Requirement for capital Adequacy Including Capital Buffer Common Equity Tier I Risk-Based Capital Ratio	7.00%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets		7.00%
Value Of Trust Preferred Securities Included In Tier 1 Capital	$ 43,000	$ 43,000				$ 43,000
Subordinated Debt	$ 59,331	$ 59,080				15,000	$ 15,000
Subordinated Debt, Phase-Out Period, Annual, Percentage	0.20
Share Repurchase Program Three [Member]
Tier 1 leverage capital ratio:
Stock Repurchased During Period, Shares | shares	488,052
Shares repurchased, average cost per share | $ / shares	$ 42.61
Stock repurchase program, shares of common stock approved for repurchase | shares					775,000
Share Repurchase Program Four [Member]
Tier 1 leverage capital ratio:
Stock Repurchased During Period, Shares | shares	274,354
Shares repurchased, average cost per share | $ / shares		$ 35.36
Stock repurchase program, shares of common stock approved for repurchase | shares				750,000
Stock Repurchase Program, Period in Force		12 months
Share Repurchase Program Five
Tier 1 leverage capital ratio:
Stock Repurchase Program, Period in Force	12 months
Share Repurchase Program Five | Subsequent Event [Member]
Tier 1 leverage capital ratio:
Stock repurchase program, shares of common stock approved for repurchase | shares			750,000
Subsidiaries [Member]
Total risk-based capital:
Actual Regulatory Capital - Amount	$ 460,611	$ 423,540
Capital To Risk Weighted Assets	0.1428	0.1345
Minimum Requirement for capital Adequacy Including Capital Buffer Total Risk-Based Capital Ratio	10.50%
Minimum Regulatory Capital Required - Ratio		0.1050
Minimum Regulatory Provision To Be Well Capitalized - Ratio	0.1000	0.1000
Tier 1 capital:
Actual Regulatory Capital - Amount	$ 420,294	$ 398,349
Actual Regulatory Capital - Ratio	0.1303	0.1265
Minimum Requirement for capital Adequacy Including Capital Buffer Tier I Risk-Based Capital Ratio	8.50%
Minimum Regulatory Capital Required - Ratio		0.0850
Minimum Regulatory Provision To Be Well Capitalized - Ratio	0.0800	0.0800
Common equity tier I capital	$ 420,294	$ 398,349
Tier 1 leverage capital ratio:
Actual Regulatory Capital - Amount	$ 420,294	$ 398,349
Actual Regulatory Capital - Ratio	0.0864	0.0919
Minimum Regulatory Capital Required - Ratio	0.0400	0.0400
Minimum Regulatory Provision To Be Well Capitalized - Ratio	0.0500	0.0500
Common Equity Tier I Risk Based Capital Ratio	13.03%	12.65%
Minimum Requirement for capital Adequacy Including Capital Buffer Common Equity Tier I Risk-Based Capital Ratio	7.00%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets		7.00%
Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier II Capital [Member]
Tier 1 leverage capital ratio:
Subordinated Debt	$ 12,000	$ 15,000				$ 15,000