Income Taxes - Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax provision
Federal	$ 35,434	$ 32,721	$ 27,564
State and Puerto Rico	6,054	4,683	4,065
Total current	41,488	37,404	31,629
Deferred tax provision (benefit)
Federal	5,391	(2,101)	(1,481)
State and Puerto Rico	(1,213)	862	1,076
Total deferred	4,178	(1,239)	(405)
Provision for income taxes	$ 45,666	$ 36,165	$ 31,224