Discontinued Operations - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(loss) on disposal of discontinued operations, net of tax	$ 0	$ 0	$ (86)
Loss from discontinued operations, net of tax	$ 0	$ 0	(242)
Trapeze [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale price for business				$ 152,100
Gain/(loss) on disposal of discontinued operations, before income tax			(200)	88,300
Gain/(loss) on disposal of discontinued operations, net of tax			(100)	$ 44,800
Escrow receivable collected			3,500
Loss from discontinued operations, net of tax			$ (200)