Summary of Significant Accounting Policies - Leases (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Option	Sep. 30, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Variable lease expense and short-term lease expenses			$ 6,200
Weighted average discount rate	4.00%		4.00%
Lease expense	$ 6,500	$ 6,100	$ 18,300	$ 17,200
Weighted average remaining lease term	8 years 1 month 6 days		8 years 1 month 6 days
Rent paid to related parties	$ 700	$ 1,300	$ 2,700	$ 3,500
Existence of option to extend			true
Summary of lease asset and liabilities
Lease right-of-use assets	84,281		$ 84,281
Lease Liabilities
Other current liabilities	$ 13,549		$ 13,549
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current		Other Liabilities, Current
Long-term lease liabilities	$ 73,213		$ 73,213
Present Value of Lease Liabilities	$ 86,762		$ 86,762
Minimum
Lessee, Lease, Description [Line Items]
Lease term	3 years		3 years
Number of options to renew | Option			1
Maximum
Lessee, Lease, Description [Line Items]
Lease term	10 years		10 years