CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income		$ 38,718	$ 39,643	$ 28,002
Other comprehensive income, net of tax:
Unrealized holding (loss)/gain on securities arising during the period, net of income taxes	[1]	10,967	11,076	(9,343)
Reclassification adjustment for net (gains) losses on sale of securities included in net income, net of income taxes	[2]	(306)	0	(5)
Other comprehensive income (loss), net of tax		10,661	11,076	(9,348)
Comprehensive income, net of tax		$ 49,379	$ 50,719	$ 18,654

[1] Income tax expense (benefit) on the unrealized gain (loss) on securities was $4.5 million for the three months ended March 31, 2019, $4.6 million for the three months ended December 31, 2018, and $(3.9) million for the three months ended March 31, 2018.

[2] Income tax expense on the reclassification adjustment for net gains losses on sale of securities included in net income was $121,000 for the three months ended March 31, 2019, $0 for the three months ended December 31, 2018, and $1,000 for the three months ended March 31, 2018.