Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Unrealized holding gains arising during the period, tax expense (benefit)	$ (3,410)	$ 6,681	$ 15,605	$ 5,843
Reclassification adjustment for gains included in net income, tax effects	4	98	699	549
Change in fair value of derivative instruments designated as cash flow hedges, tax expense (benefit)	$ 78	$ (1,837)	$ (3,397)	$ (201)