Contract Revenue and Percentage of Completion Method - Revenues from Major Customers (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Jun. 30, 2014 |
Mar. 31, 2014 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Revenue, Major Customer [Line Items] | |||||||||||
| Revenue | $ 55,018 | $ 67,531 | $ 84,338 | $ 99,233 | $ 124,760 | $ 118,020 | $ 129,169 | $ 134,690 | $ 306,120 | $ 506,639 | $ 608,326 |
| Customer A | |||||||||||
| Revenue, Major Customer [Line Items] | |||||||||||
| Revenue | 55,775 | 160,173 | |||||||||
| Customer B | |||||||||||
| Revenue, Major Customer [Line Items] | |||||||||||
| Revenue | $ 36,320 | ||||||||||
| Customer C | |||||||||||
| Revenue, Major Customer [Line Items] | |||||||||||
| Revenue | $ 98,644 | ||||||||||
| Customer D | |||||||||||
| Revenue, Major Customer [Line Items] | |||||||||||
| Revenue | 216,875 | ||||||||||
| Customer E | |||||||||||
| Revenue, Major Customer [Line Items] | |||||||||||
| Revenue | $ 148,539 | ||||||||||