Collateralized Receivables and Transfers of Financial Assets, Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes and other receivables, net	$ 145,760		$ 145,760		$ 81,179
Secured debt	2,822,640		2,822,640		2,819,567
Interest income and expense, net	3,300	$ 3,500	9,900	$ 10,300
Collateralized Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Allowance	869		$ 869		$ 607
Receivable With Imputed Interest, Term			15 years 6 months		15 years 8 months 12 days
Receivable with Imputed Interest, Effective Yield (Interest Rate)			10.00%		10.00%
Carrying Value [Member] | Secured Debt [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured debt	134,884		$ 134,884		$ 144,477
Carrying Value [Member] | Collateralized Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes and other receivables, net	$ 134,000		$ 134,000		$ 143,870