CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest expense related to derivatives reclassified from accumulated other comprehensive income	$ 3,470	$ 3,228	$ 7,066	$ 6,884
Net security gains reclassified from accumulated other comprehensive income	(259)	1,392	1,182	3,874
Income tax expense reclassified from accumulated other comprehensive income	7,451	8,059	12,574	13,589
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Derivatives
Interest expense related to derivatives reclassified from accumulated other comprehensive income	30	300	227	697
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Unrealized Investment Gain (Loss)
Net security gains reclassified from accumulated other comprehensive income	259	1,392	1,182	3,874
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Other Comprehensive Income (Loss)
Income tax expense reclassified from accumulated other comprehensive income	$ (61)	$ 407	$ 201	$ 1,185