Loans and Finance Receivables Held for Investment and Allowance for Credit Losses (Allowance Roll Forward) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance	$ 145,739	$ 124,058	$ 140,040	$ 109,015
Recoveries of previously charged off amounts	4,652	3,306	13,089	9,857
Loans and finance receivables charged off	(45,442)	(32,822)	(134,422)	(93,916)
Provision for credit losses	43,096	39,102	129,338	108,688
Allowance for credit losses, ending balance	$ 148,045	$ 133,644	$ 148,045	$ 133,644