Income Taxes - Schedule of Unrecognized Tax Benefits Roll Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 38,678	$ 26,140	$ 28,567
Additions for tax positions of prior periods	24,804	3,450	3,525
Additions for tax positions of the current period	4,174	9,012	3,299
Additions due to acquisitions	0	5,049	6,177
Reductions for tax positions of prior periods	(11,162)	(1,165)	(12,206)
Reductions attributable to settlements with taxing authorities	(1,536)	(568)	(142)
Reductions attributable to lapses of applicable statute of limitations	(2,769)	(3,240)	(3,080)
Ending balance	$ 52,189	$ 38,678	$ 26,140