Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Leases [Line Items]
Description of expiration date for operating leases	various dates through 2030		various dates through 2030
Description of expiration date for sublease	various dates through 2025		various dates through 2025
Description of expiration date for office equipment pursuant to finance leases	various dates through 2022		various dates through 2022
Rent expense		$ 6.0		$ 12.3
Irrevocable Standby Letters of Credit
Leases [Line Items]
Letter of credit					$ 4.7