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Related Party Transactions - Payables to Related Parties (Details) - USD ($)			12 Months Ended
	Mar. 19, 2018	Mar. 19, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Nov. 30, 2018
Related Party Transaction [Line Items]
Payables to related parties			$ 13,507,000		$ 38,090,000
Receivables from related parties			20,498,000		$ 0
Intercompany Credit Agreement
Related Party Transaction [Line Items]
Interest expense			$ 8,900,000	$ 100,000
Basis spread on variable rate		1.00%
Cantor Credit Agreement \| Cantor
Related Party Transaction [Line Items]
Maximum revolving credit						$ 250,000,000
Basis spread on variable rate	1.00%