Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 12 Months Ended | |||
---|---|---|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2017 |
Mar. 31, 2018 |
Dec. 31, 2018 |
Mar. 31, 2017 |
Mar. 31, 2016 |
|
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | ||||||
Increase (decrease) in retained earnings | $ 690,516 | $ 937,663 | ||||
Accounting Standards Update 2014-09 | ||||||
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | ||||||
Cumulative effect on retained earnings | 7,900 | |||||
Restatement Adjustment | Accounting Standards Update 2014-09 | ||||||
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | ||||||
Increase (decrease) in retained earnings | $ (3,400) | $ 8,400 | $ 2,900 | |||
Restatement Adjustment | Accounting Standards Update 2017-07 | ||||||
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] | ||||||
Reclassification of net periodic benefit cost | $ 1,900 | $ 5,700 |