Long-Term Debt - Schedule of Outstanding Senior Notes Issuances (Details) - USD ($) |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Debt Instrument [Line Items] | ||
| Less: unamortized issuance costs | $ 7,700,000 | $ 7,806,000 |
| Senior notes, net | 254,800,000 | 254,694,000 |
| Senior Notes | ||
| Debt Instrument [Line Items] | ||
| Principal amount | 262,500,000 | 262,500,000 |
| Less: unamortized issuance costs | 7,700,000 | 7,806,000 |
| Senior notes, net | 254,800,000 | 254,694,000 |
| Senior Notes | 2016 Senior Notes | ||
| Debt Instrument [Line Items] | ||
| Principal amount | 110,000,000 | 110,000,000 |
| Less: unamortized issuance costs | 3,588,000 | 3,610,000 |
| Senior notes, net | 106,412,000 | 106,390,000 |
| Original debt issuance costs | $ 3,715,000 | |
| Coupon rate | 6.625% | |
| Effective interest rate | 7.07% | |
| Senior Notes | 2013 Senior Notes | ||
| Debt Instrument [Line Items] | ||
| Principal amount | $ 152,500,000 | 152,500,000 |
| Less: unamortized issuance costs | 4,112,000 | 4,196,000 |
| Senior notes, net | 148,388,000 | $ 148,304,000 |
| Original debt issuance costs | $ 5,054,000 | |
| Coupon rate | 7.75% | |
| Effective interest rate | 8.04% |