Commitments and Contingencies - Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Operating Leases
Lease Term			6 years
As Lessor
Remainder of 2018	$ 11,875		$ 11,875
2019	23,619		23,619
2020	21,928		21,928
2021	17,336		17,336
2022	9,085		9,085
2023 and Thereafter	8,621		8,621
Total future minimum lease payments	92,464		92,464
As Lessee
Remainder of 2018	7,016		7,016
2019	12,914		12,914
2020	11,612		11,612
2021	7,032		7,032
2022	1,554		1,554
2023 and Thereafter	2,290		2,290
Total future minimum lease payments	42,418		42,418
Rental expense and rental income for all operating leases
Rental expense for all operating lease	3,600	$ 3,400	7,000	$ 6,900
Prepaid rent and security deposit	11,100		11,100		$ 11,300
Prepaid expenses and other current assets
Rental expense and rental income for all operating leases
Prepaid rent and security deposit	1,800		1,800		1,800
Other assets
Rental expense and rental income for all operating leases
Prepaid rent and security deposit	$ 9,300		$ 9,300		$ 9,500