Summary of Significant Accounting Policies - Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Finance Lease, Right-Of-Use Asset, Real Estate Assets, Percent	66.00%
Operating Lease, Right-Of-Use Asset, Real Estate Assets, Percent	98.00%
Sublease income	$ 3,047
Finance Lease, Right-Of-Use Asset, Non-Real Estate Assets, Percent	34.00%
Minimum
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term	5 years
Lessee, operating lease, renewal term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term	10 years
Lessee, operating lease, renewal term	5 years
Vehicle And Equipment | Minimum
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term	1 year
Vehicle And Equipment | Maximum
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term	7 years
Accounting Standards Update 2016-02 [Member]
Lessee, Lease, Description [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 5,781	$ 5,800