Long-Term Debt - Narrative (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Jun. 27, 2017 |
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
Dec. 31, 2016 |
|
| Debt Instrument [Line Items] | ||||||
| Accelerated amortization of senior note issuance cost | $ 0 | $ 0 | $ 2,809,000 | $ 2,345,000 | ||
| Interest expense | 4,829,000 | 6,856,000 | 18,430,000 | 21,314,000 | ||
| Senior Notes [Member] | ||||||
| Debt Instrument [Line Items] | ||||||
| Principal amount | 262,500,000 | 262,500,000 | $ 362,500,000 | |||
| Interest expense | 4,776,000 | 6,776,000 | 18,218,000 | 21,049,000 | ||
| Accrued interest | 1,342,000 | 1,342,000 | 1,453,000 | |||
| Amortization expense, debt issuance costs | 53,000 | $ 80,000 | 212,000 | $ 265,000 | ||
| 2012 Senior Notes [Member] | Senior Notes [Member] | ||||||
| Debt Instrument [Line Items] | ||||||
| Redemption price percentage | 100.00% | |||||
| Principal amount | $ 100,000,000 | $ 0 | $ 0 | $ 100,000,000 | ||
| Accelerated amortization of senior note issuance cost | $ 2,809,000 | |||||