CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest expense related to derivatives reclassified from accumulated other comprehensive income	$ 3,660	$ 3,790	$ 10,726	$ 10,674
Net security gains reclassified from accumulated other comprehensive income	(145)	1,679	1,037	5,553
Income tax expense (benefit) reclassified from accumulated other comprehensive income	8,956	8,725	21,530	22,314
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Derivatives
Interest expense related to derivatives reclassified from accumulated other comprehensive income	242	308	469	1,005
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Unrealized Investment Gain (Loss)
Net security gains reclassified from accumulated other comprehensive income	145	1,679	1,037	5,553
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Other Comprehensive Income (Loss)
Income tax expense (benefit) reclassified from accumulated other comprehensive income	$ (26)	$ 511	$ 174	$ 1,696