Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets and Liabilities - Schedule Of Other Finite-Lived Intangile Assets (Details) - Other finite-lived intangible assets - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets
Amortization period	4 years
Finite-Lived Intangible Assets, Gross	$ 20,974	$ 20,929
Finite-Lived Intangible Assets, Accumulated Amortization	(11,936)	(10,728)
Finite-Lived Intangible Assets, Net	$ 9,038	$ 10,201

Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets and Liabilities - Schedule Of Other Finite-Lived Intangile Assets (Details) - Other finite-lived intangible assets - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Finite-Lived Intangible Assets

Amortization period

4 years

Finite-Lived Intangible Assets, Gross

$ 20,974

$ 20,929

Finite-Lived Intangible Assets, Accumulated Amortization

(11,936)

(10,728)

Finite-Lived Intangible Assets, Net

$ 9,038

$ 10,201