Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Details)

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Income Taxes (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Income Tax Disclosure [Abstract]      
Income tax provision (benefit) $ 4,709,000 $ (2,816,000)  
Unrecognized tax benefits 8,500,000   $ 8,700,000
Unrecognized tax benefits, income tax penalties and interest accrued $ 6,700,000   6,500,000
Income Tax Contingency [Line Items]      
Income tax benefit due to the Tax Act     4,600,000
Impact due to repatriation charge     0
Repatriation charge     $ 18,500,000