Quarterly Results of Operations (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]
Interest income	$ 113,224	$ 106,225	$ 109,252	$ 119,807	$ 125,821	$ 118,132	$ 112,639	$ 108,813	$ 448,508	$ 465,405	$ 407,944
Interest expense	10,913	13,304	16,234	25,930	28,237	29,200	27,361	23,947	66,381	108,745	69,087
NET INTEREST INCOME	102,311	92,921	93,018	93,877	97,584	88,932	85,278	84,866	382,127	356,660	338,857
Provision for loan losses	4,482	12,544	21,895	19,752	500	600	500	1,200	58,673	2,800	7,227
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	97,829	80,377	71,123	74,125	97,084	88,332	84,778	83,666	323,454	353,860	331,630
Non-interest income	27,483	26,163	26,481	29,799	24,245	22,116	21,614	18,713	109,926	86,688	76,459
Non-interest expense	72,536	64,709	59,989	66,171	65,201	67,354	57,587	56,621	263,405	246,763	219,951
Income before income tax expense	52,776	41,831	37,615	37,753	56,128	43,094	48,805	45,758
Income tax expense	7,641	5,621	4,623	3,490	8,298	6,337	7,749	6,941	21,375	29,325	28,999
Net income available to common stockholders	$ 45,135	$ 36,210	$ 32,992	$ 34,263	$ 47,830	$ 36,757	$ 41,056	$ 38,817	$ 148,600	$ 164,460	$ 159,139
Basic EPS (in dollars per share)	$ 0.83	$ 0.67	$ 0.62	$ 0.63	$ 0.87	$ 0.71	$ 0.83	$ 0.79	$ 2.75	$ 3.20	$ 3.23
Diluted EPS (in dollars per share)	$ 0.83	$ 0.67	$ 0.62	$ 0.62	$ 0.87	$ 0.71	$ 0.83	$ 0.78	$ 2.74	$ 3.19	$ 3.22
Average Shares Outstanding:
Basic (in shares)	53,899,501	53,843,508	53,762,913	54,732,073	55,348,176	51,433,227	49,432,167	49,369,024	54,058,471	51,412,133	49,262,015
Diluted (in shares)	54,049,574	53,970,598	53,942,567	54,917,760	55,519,953	51,569,557	49,549,887	49,540,844	54,220,384	51,561,238	49,470,923