Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 261,988	$ 161,441	$ 121,027
Other comprehensive income (loss)
Net unrealized holding gains (losses) arising during period on investment securities available for sale, net of tax expense (benefit) of $4,084, $6,211 and ($849)	15,363	23,365	(3,196)
Reclassification adjustment for gains on investment securities included in earnings, net of tax of $0, $12 and $19	0	(46)	(70)
Net unrealized gains (losses) on cash flow hedge during the period, net of tax expense (benefit) of $39, ($133) and $30	147	(498)	112
Total other comprehensive income (loss)	15,510	22,821	(3,154)
Comprehensive income	$ 277,498	$ 184,262	$ 117,873