Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |||
---|---|---|---|---|---|
Mar. 31, 2018 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Jan. 01, 2019 |
|
Summary Of Significant Policies [Line Items] | |||||
Loss on extinguishment of debt | $ 2,200 | $ 2,209 | $ 0 | $ 0 | |
Scenario, Forecast | Accounting Standards Update 2016-02 | Minimum | |||||
Summary Of Significant Policies [Line Items] | |||||
Operating lease, liability | $ 44,000 | ||||
Operating lease, right-of-use asset | 44,000 | ||||
Scenario, Forecast | Accounting Standards Update 2016-02 | Maximum | |||||
Summary Of Significant Policies [Line Items] | |||||
Operating lease, liability | 49,000 | ||||
Operating lease, right-of-use asset | $ 49,000 |