Loans and Finance Receivables Held for Investment and Allowance for Credit Losses (Allowance Roll Forward) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance	$ 147,406	$ 118,921	$ 140,040	$ 109,015
Recoveries of previously charged off amounts	4,523	3,206	8,437	6,551
Loans and finance receivables charged off	(49,141)	(31,362)	(88,980)	(61,094)
Provision for credit losses	42,951	33,293	86,242	69,586
Allowance for credit losses, ending balance	$ 145,739	$ 124,058	$ 145,739	$ 124,058