Debt Obligations - Information on Borrowings under Current and Prior Credit Facility and Applicable Interest Rates (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Maximum amount outstanding under the senior credit facility during the period	$ 2,023,326	$ 2,051,714	$ 1,300,401
Average daily amount outstanding under the senior credit facility	$ 1,091,091	$ 1,553,499	$ 914,012
Weighted-average interest rate of the senior credit facility	2.10%	3.80%	3.60%

The average effective interest rate during the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration