Summary Of Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total interest income	$ 133,296	$ 127,384	$ 126,232	$ 130,897	$ 133,109	$ 132,533	$ 135,422	$ 128,888	$ 517,809	$ 529,952	$ 497,069
Total interest expense	2,184	2,658	4,381	8,475	8,292	10,083	10,306	7,866	17,698	36,547	18,230
Net Interest Income	131,112	124,726	121,851	122,422	124,817	122,450	125,116	121,022	500,111	493,405	478,839
Provision (recapture) for credit losses	(4,700)	7,400	33,500	41,500	1,614	299	218	1,362	77,700	3,493	14,769
Noninterest income	23,562	22,472	37,259	21,207	21,807	28,030	25,648	21,696	104,500	97,181	88,256
Noninterest expense	84,300	85,115	80,833	84,271	86,978	87,076	86,728	84,700	334,519	345,482	340,490
Income before income taxes	75,074	54,683	44,777	17,858	58,032	63,105	63,818	56,656	192,392	241,611	211,836
Income Tax Expense (Benefit)	16,774	9,949	8,195	3,230	11,903	12,378	12,094	10,785	38,148	47,160	38,954
Net income	$ 58,300	$ 44,734	$ 36,582	$ 14,628	$ 46,129	$ 50,727	$ 51,724	$ 45,871	$ 154,244	$ 194,451	$ 172,882
Per Common Share
Earnings (basic)	$ 0.82	$ 0.63	$ 0.52	$ 0.20	$ 0.64	$ 0.70	$ 0.71	$ 0.63	$ 2.17	$ 2.68	$ 2.36
Earnings (diluted)	$ 0.82	$ 0.63	$ 0.52	$ 0.20	$ 0.64	$ 0.70	$ 0.71	$ 0.63	$ 2.17	$ 2.68	$ 2.36