Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Change in tax rate, provisional Income tax expense (benefit)			$ 0		$ (26,900,000)
Income tax provision (benefit)	$ (16,272,000)	$ 4,213,000	$ (23,552,000)	$ 28,512,000
Effective income tax rate	15.60%	62.40%	16.80%	39.60%
Valuation allowance	$ 11,900,000		$ 11,900,000		$ 10,500,000
Unrecognized tax benefits	25,500,000		25,500,000
Unrecognized tax benefits that would impact the Company's effective tax rate	2,900,000		2,900,000
Unrecognized tax benefits that would impact goodwill	22,600,000		22,600,000
Unrecognized tax benefits, income tax penalties expense			0
Unrecognized tax benefits, interest on income taxes expense			700,000
Unrecognized tax benefits, income tax penalties accrued	8,900,000		8,900,000
Unrecognized tax benefits, interest on income taxes accrued	$ 6,700,000		$ 6,700,000