Debt - Senior Unsecured Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Total Principal	$ 1,371,238
Long-term Debt, Total	1,370,999
Senior Unsecured Debt [Member]
Total Principal	860,000	$ 860,000
Unamortized debt issuance costs and original issue discount	(4,546)	(4,672)
Long-term Debt, Total	855,454	855,328
Senior Unsecured Debt [Member] | 2025 Senior Unsecured Notes [Member]
Total Principal	50,000	50,000
Senior Unsecured Debt [Member] | 2027 Senior Unsecured Notes [Member]
Total Principal	50,000	50,000
Senior Unsecured Debt [Member] | 2028 Senior Unsecured Notes [Member]
Total Principal	60,000	60,000
Senior Unsecured Debt [Member] | 2029 Senior Unsecured Notes [Member]
Total Principal	100,000	100,000
Senior Unsecured Debt [Member] | 2030 Senior Unsecured Notes [Member]
Total Principal	125,000	125,000
Senior Unsecured Debt [Member] | 2030 Senior Unsecured Public Notes [Member]
Total Principal	350,000	350,000
Senior Unsecured Debt [Member] | 2031 Senior Unsecured Notes [Member]
Total Principal	$ 125,000	$ 125,000