Debt - Additional Information - Senior Unsecured Notes (Details) - USD ($) |
12 Months Ended | ||||
|---|---|---|---|---|---|
Aug. 18, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Mar. 31, 2015 |
|
| Debt Instrument [Line Items] | |||||
| Proceeds from issuance of senior unsecured notes, net of transaction fees and expenses | $ 0 | $ 298,134,000 | $ 0 | ||
| Senior Unsecured Notes | |||||
| Debt Instrument [Line Items] | |||||
| Aggregate principal amount of senior unsecured notes | $ 300,000,000 | ||||
| Debt percentage issued of their principal amount | 99.378% | ||||
| Proceeds from issuance of senior unsecured notes, net of transaction fees and expenses | $ 296,200,000 | ||||
| Stated interest rate | 4.45% | ||||
| Redemption price percentage of principal amount redeemed | 100.00% | ||||
| Deferred financing costs, gross | $ 3,400,000 | $ 4,800,000 | |||
| Unamortized deferred financing costs | $ 3,000,000 | $ 3,100,000 | |||