Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Retained Earnings	AOCI Attributable to Parent [Member]	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2016				$ 0	$ 305,826	$ 535,631	$ (81,472)	$ (17,745)
Beginning balance, shares at Dec. 31, 2016				0	15,340,718
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	$ 84,242					84,242
Other Comprehensive Income (Loss), Net of Tax	(8,709)							(8,709)
Dividends, Common Stock, Cash						57,883
Stock Issued During Period, Shares, Dividend Reinvestment Plan					55
Stock Issued During Period, Value, Dividend Reinvestment Plan					$ 6
Allocated Share-based Compensation Expense	$ 2,700				$ 2,701
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures					6,381
Stock Granted, Value, Share-based Compensation, Net of Forfeitures					$ 795	197	645
Treasury Stock, Shares, Acquired					70,000
Treasury Stock, Value, Acquired, Cost Method							(7,378)
Treasury Stock Reissued Shares For Director Grants	11,150				11,150
Treasury shares reissued for director grants						115	1,126
Ending balance, shares at Dec. 31, 2017				0	15,288,194
Ending balance at Dec. 31, 2017				$ 0	$ 307,726	561,908	(87,079)	(26,454)
Ending balance (Adjustments for New Accounting Pronouncement [Member]) at Dec. 31, 2017						563,825		(27,449)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ (995)							(3,806)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets | Accounting Standards Update 2016-01 [Member]						1,917			$ (995)
Cumulative Effect of New Accounting Principle in Period of Adoption | Adjustments for New Accounting Pronouncement [Member]		$ 3,806	$ (3,806)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	110,387					110,387
Other Comprehensive Income (Loss), Net of Tax	(18,533)							(18,533)
Dividends, Common Stock, Cash						63,555
Stock Issued During Period, Shares, Dividend Reinvestment Plan					44
Stock Issued During Period, Value, Dividend Reinvestment Plan					$ 4
Allocated Share-based Compensation Expense	$ 4,000				$ 3,954
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures					12,921
Stock Granted, Value, Share-based Compensation, Net of Forfeitures					$ 1,597	317	1,304
Treasury Stock, Shares, Acquired					50,000
Treasury Stock, Value, Acquired, Cost Method							(5,784)
Treasury Stock Reissued Shares For Director Grants	11,650				11,650
Treasury shares reissued for director grants						77	1,186
Stock Issued During Period, Shares, Acquisitions	435,457				435,457
Stock Issued During Period, Value, Acquisitions					$ 48,519
Ending balance, shares at Dec. 31, 2018				0	15,698,178
Ending balance at Dec. 31, 2018	$ 832,506			$ 0	$ 358,598	614,069	(90,373)	(49,788)
Ending balance (Adjustments for New Accounting Pronouncement [Member]) at Dec. 31, 2018						613,926
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						(143)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	102,700					102,700
Other Comprehensive Income (Loss), Net of Tax	40,199							40,199
Dividends, Common Stock, Cash						69,482
Stock Issued During Period, Shares, Dividend Reinvestment Plan					171
Stock Issued During Period, Value, Dividend Reinvestment Plan					$ 3
Allocated Share-based Compensation Expense	$ 5,000				$ 4,999
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures					18,983
Stock Granted, Value, Share-based Compensation, Net of Forfeitures					$ 2,480	273	1,926
Treasury Stock, Shares, Acquired					421,253
Treasury Stock, Value, Acquired, Cost Method							(40,535)
Treasury Stock Reissued Shares For Director Grants	13,500				13,500
Treasury shares reissued for director grants						24	1,349
Stock Issued During Period, Shares, Acquisitions	1,037,205				1,037,205
Stock Issued During Period, Value, Acquisitions					$ 98,275
Ending balance, shares at Dec. 31, 2019				0	16,346,442
Ending balance at Dec. 31, 2019	$ 969,014			$ 0	$ 459,389	$ 646,847	$ (127,633)	$ (9,589)