Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Securities gains (losses)	$ 522	$ (106)	$ (211)
Tax expense (benefit)	19,118	18,531	19,146
Net income	47,346	46,432	43,251
Unrealized Gains (Losses) on AFS Securities [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Securities gains (losses)	522	(106)	(211)
Tax expense (benefit)	183	(37)	(74)
Net income	$ 339	$ (69)	$ (137)