Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Lease expense	$ 14,168	$ 14,601	$ 41,289	$ 44,504
Short term lease expense	115	1,014	332	3,517
Variable lease expense	329	1,011	430	1,416
Sublease income	(338)	(769)	(514)	(2,538)
Total operating lease expense	14,274	15,857	41,537	46,899
Offices
Lessee, Lease, Description [Line Items]
Lease expense	6,969	8,515	20,770	27,077
Short term lease expense	115	496	332	1,944
Variable lease expense	307	406	320	458
Sublease income	(338)	(769)	(514)	(2,538)
Total operating lease expense	7,053	8,648	20,908	26,941
Data Centers
Lessee, Lease, Description [Line Items]
Lease expense	7,199	6,086	20,519	17,427
Short term lease expense	0	518	0	1,573
Variable lease expense	22	605	110	958
Sublease income	0	0	0	0
Total operating lease expense	$ 7,221	$ 7,209	$ 20,629	$ 19,958