Long-Term Debt - Narrative (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
Dec. 31, 2018 |
|
| Debt Instrument [Line Items] | |||||
| Interest expense | $ 4,830 | $ 4,829 | $ 9,659 | $ 9,658 | |
| Senior Notes | |||||
| Debt Instrument [Line Items] | |||||
| Interest expense | 4,777 | 4,776 | 9,553 | 9,553 | |
| Accrued interest | 1,342 | 1,342 | $ 1,342 | ||
| Amortization expense, debt issuance costs | $ 53 | $ 53 | $ 106 | $ 105 | |
| 2013 Senior Notes | Senior Notes | |||||
| Debt Instrument [Line Items] | |||||
| Redemption price, percentage | 100.00% | ||||
| Minimum | 2013 Senior Notes | Senior Notes | |||||
| Debt Instrument [Line Items] | |||||
| Prior notice to be given before redemption date | 30 days | ||||
| Maximum | 2013 Senior Notes | Senior Notes | |||||
| Debt Instrument [Line Items] | |||||
| Prior notice to be given before redemption date | 60 days | ||||