Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 112,828	$ 104,866	$ 98,827
Unrealized loss from securities:
Net unrealized holding loss from available for sale securities arising during the period, net of tax of $1,932, $7,025 and $3,455	(3,391)	(12,338)	(6,069)
Reclassification adjustment of net gain (loss) from sale of available for sale securities included in income, net of tax of ($4), $429 and $574	7	(752)	(1,007)
Net unrealized loss from securities, net of reclassification adjustment	(3,384)	(13,090)	(7,076)
Pension plan liability adjustment:
Unrecognized net actuarial gain (loss) and plan amendments during the period, net of tax of $2,287, $22 and $2,878	4,017	(39)	(5,054)
Less: amortization of unrecognized net actuarial losses included in net periodic pension cost, net of tax of ($127), ($243) and ($122)	223	425	214
Pension plan liability adjustment, net	4,240	386	(4,840)
Other comprehensive income (loss)	856	(12,704)	(11,916)
Comprehensive income	$ 113,684	$ 92,162	$ 86,911