Consolidated Condensed Statements Of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Treasury Stock At Cost [Member]	Accumulated Other Comprehensive Income (loss) [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption | Adjustments for New Accounting Pronouncement [Member]				$ 3,806		$ (3,806)
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
Balance at Dec. 31, 2017		$ 0	$ 307,726	561,908	$ (87,079)	(26,454)
Balance (Accounting Standards Update 2016-01 [Member]) at Dec. 31, 2017		0	307,726	563,825	(87,079)	(27,449)
Net Income				31,123
Other comprehensive income, net of tax:
Dividends on common shares				(14,496)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(1,597)	(317)	(1,304)
Share-based Payment Arrangement, Expense			1,121
Balance at Mar. 31, 2018		0	307,249	583,941	(85,775)	(52,641)
Balance at Dec. 31, 2017		0	307,726	561,908	(87,079)	(26,454)
Balance (Accounting Standards Update 2016-01 [Member]) at Dec. 31, 2017		0	307,726	563,825	(87,079)	(27,449)
Net Income	59,364
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	(25,778)
Share-based Payment Arrangement, Expense	2,000
Balance at Jun. 30, 2018		0	308,144	593,512	(91,559)	(55,009)
Balance at Mar. 31, 2018		0	307,249	583,941	(85,775)	(52,641)
Net Income	28,241			28,241
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	(2,368)
Dividends on common shares				(18,670)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Share-based Payment Arrangement, Expense	900		896
Treasury Stock, Value, Acquired, Cost Method					5,784
Balance at Jun. 30, 2018		0	308,144	593,512	(91,559)	(55,009)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets				143
Balance at Dec. 31, 2018	832,506	0	358,598	614,069	(90,373)	(49,788)
Balance (Adjustments for New Accounting Pronouncement [Member]) at Dec. 31, 2018				613,926
Net Income				25,455
Other comprehensive income, net of tax:
Dividends on common shares				(19,137)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			(2,480)	(273)	(1,926)
Share-based Payment Arrangement, Expense			1,358
Treasury Stock, Value, Acquired, Cost Method					8,502
Balance at Mar. 31, 2019		0	357,475	619,971	(96,949)	(35,453)
Balance at Dec. 31, 2018	832,506	0	358,598	614,069	(90,373)	(49,788)
Balance (Adjustments for New Accounting Pronouncement [Member]) at Dec. 31, 2018				613,926
Net Income	47,618
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	23,508
Share-based Payment Arrangement, Expense	2,500
Balance at Jun. 30, 2019	934,432	0	456,911	625,227	(121,399)	(26,307)
Balance at Mar. 31, 2019		0	357,475	619,971	(96,949)	(35,453)
Net Income	22,163			22,163
Other comprehensive income, net of tax:
Unrealized net holding (loss) gain on securities available-for-sale, net of income taxes	8,967
Dividends on common shares				(16,907)
Cash payment for fractional shares in dividend reinvestment plan			(1)
Share-based Payment Arrangement, Expense	1,200		1,162
Treasury Stock, Value, Acquired, Cost Method					24,450
Proceeds from Issuance of Common Stock			98,275
Balance at Jun. 30, 2019	$ 934,432	$ 0	$ 456,911	$ 625,227	$ (121,399)	$ (26,307)