Commitments, Contingencies, and Guarantees - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) Building	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2012 USD ($)
Commitments Contingencies And Guarantees [Line Items]
Number of buildings in corporate headquarters | Building	3
Operating leases rental expense total	$ 7,900,000	$ 6,700,000	$ 5,800,000
Outstanding claims for payment			2,000,000
Proceeds from legal settlements			2,000,000
Minimum
Commitments Contingencies And Guarantees [Line Items]
Non-payment of outstanding invoices				$ 6,500,000
Selling, General and Administrative
Commitments Contingencies And Guarantees [Line Items]
Bad debt recovery			$ 2,000,000