CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income		$ 38,527	$ 38,718	$ 27,303	$ 77,245	$ 55,305
Other comprehensive income, net of tax:
Unrealized holding gain (loss) on securities available-for-sale arising during the period, net of income taxes	[1]	17,449	10,967	(3,122)	28,416	(12,465)
Reclassification adjustment for net gain on sale of securities included in net income, net of income taxes	[2]	(151)	(306)	(240)	(457)	(245)
Other comprehensive income (loss), net of tax		17,298	10,661	(3,362)	27,959	(12,710)
Comprehensive income, net of tax		$ 55,825	$ 49,379	$ 23,941	$ 105,204	$ 42,595

[1] Income tax expense (benefit) on the unrealized gain (loss) on securities was $7.1 million for the three months ended June 30, 2019, $4.5 million for the three months ended March 31, 2019, $(1.3) million for the three months ended June 30, 2018, $11.6 million for the six months ended June 30, 2019 and $(5.2) million for the six months ended June 30, 2018.

[2] Income tax expense on the reclassification adjustment for net gains losses on sale of securities included in net income was $61,000 for the three months ended June 30, 2019, $121,000 for the three months ended March 31, 2019, $90,000 for the three months ended June 30, 2018, $182,000 for the six months ended June 30, 2019 and $91,000 for the six months ended June 30, 2018.