Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate (as a percent)	9.10%	16.50%	16.90%	18.60%
Provision for income taxes	$ 7,800,000	$ 13,600,000	$ 41,900,000	$ 44,300,000
Tax benefit from the release of valuation allowance in a foreign jurisdiction and reserves for uncertain tax positions	9,600,000	$ 4,200,000	$ 1,300,000	$ 9,100,000
Effective income tax rate excluding discrete benefits (as a percent)			21.30%	24.20%
Estimated annual effective income tax rate			24.00%		25.00%
U.S. federal statutory income tax rate (as a percent)			21.00%		35.00%
Tax cuts and jobs act, adjustments to previous estimated value	$ 0