Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 45,902	$ 49,038	$ 42,426
Expected amortization expense, 2018	38,400
Expected amortization expense, 2019	35,300
Expected amortization expense, 2020	34,500
Expected amortization expense, 2021	33,200
Expected amortization expense, 2022	$ 31,600