Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Unrealized holding gains arising during the period net of tax effects	$ 13,702	$ 5,408
Reclassification adjustment for gains included in net income net of tax effects	69	135
Change in fair value of derivative instruments designated as cash flow hedges net of tax effects	$ 2,223	$ 0