Revenue (Contract Assets and Liabilities) (Details) - Contract Asset [Member] - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Jan. 01, 2018 |
|
| Capitalized Contract Cost [Line Items] | ||
| Balances at December 31, 2017 | $ 0 | |
| Adoption of ASC 606 | $ (40,854) | |
| Contract assets transferred to receivables | 1,315 | |
| Additions to contract assets | 21,127 | |
| Balances at March 31, 2018 | $ 60,666 |