Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 54,528	$ 56,693	$ 15,584
Additions	16,284	28,509	41,553
Deductions	(35,197)	(30,674)	(444)
Balance at End of Year	35,615	54,528	56,693
Reserve for program development costs [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	31,652	34,798	13,109
Additions	9,328	26,191	21,689
Deductions	(33,348)	(29,337)	0
Balance at End of Year	7,632	31,652	34,798
Reserve for program development costs [Member] | Two Funds Not Yet Offering
Movement in Valuation Allowances and Reserves [Roll Forward]
Deductions	(1,300)
Reserve for program development costs [Member] | CCPT V
Movement in Valuation Allowances and Reserves [Roll Forward]
Deductions	(32,000)
Allowance for doubtful accounts and other reserves [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	7,576	6,595	2,475
Additions	6,956	2,318	4,564
Deductions	(1,849)	(1,337)	(444)
Balance at End of Year	12,683	7,576	6,595
Allowance for doubtful accounts and other reserves [Member] | Discontinued Operations
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at End of Year	1,000
Unsecured note reserve [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	15,300	15,300	0
Additions	0	0	15,300
Deductions	0	0	0
Balance at End of Year	$ 15,300	$ 15,300	$ 15,300