Agreements and Transactions with Related Parties (Narratives) (Details) - USD ($)				3 Months Ended		9 Months Ended		12 Months Ended
	May 31, 2016	Feb. 20, 2016	Feb. 02, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jul. 31, 2016	Apr. 30, 2016	Jan. 20, 2016	Dec. 31, 2014
Distributions Of Available Cash and Deferred Revenue Earned
Advisory revenue				$ 45,176,000	$ 33,490,000	$ 128,859,000	$ 135,279,000
Percentage of available cash distribution to advisor						10.00%
Other Transactions with Affiliates
Proceeds from repayment of short-term loans to affiliates						$ 37,053,000	50,000,000
Gain on sale of property						$ 68,070,000	$ 2,980,000
Self-storage
Other Transactions with Affiliates
Ownership interest in joint ventures			38.30%
Self-storage | Third Party
Other Transactions with Affiliates
Ownership interest in joint ventures			61.20%
Maximum
Other Transactions with Affiliates
Ownership interest in joint ventures						90.00%
Minimum
Other Transactions with Affiliates
Ownership interest in joint ventures						3.00%
CPA: 17 - Global
Other Transactions with Affiliates
Line of credit, maximum borrowing amount								$ 75,000,000				$ 75,000,000
CPA:18 - Global
Other Transactions with Affiliates
Line of credit, maximum borrowing amount								100,000,000	$ 50,000,000			100,000,000
CWI
Other Transactions with Affiliates
Line of credit, maximum borrowing amount								110,000,000				110,000,000
CWI 2
Other Transactions with Affiliates
Line of credit, maximum borrowing amount								110,000,000.0				110,000,000.0
Loans receivable, related party											$ 20,000,000
Proceeds from repayment of short-term loans to affiliates		$ 20,000,000
CCIF
Distributions Of Available Cash and Deferred Revenue Earned
Reimbursement percentage						50.00%
Other Transactions with Affiliates
Line of credit, maximum borrowing amount								50,000,000				$ 50,000,000
Managed Programs
Other Transactions with Affiliates
Loans receivable, related party								$ 185,400,000
Managed Programs | LIBOR
Other Transactions with Affiliates
Interest rate on loan								1.10%
CESH I
Distributions Of Available Cash and Deferred Revenue Earned
Advisory revenue				$ 500,000		$ 500,000
Other Transactions with Affiliates
Line of credit, maximum borrowing amount										$ 35,000,000
Loans receivable, related party	$ 17,100,000
CESH I | LIBOR
Other Transactions with Affiliates
Interest rate on loan	1.10%
Employee | Self-storage
Other Transactions with Affiliates
Ownership interest in joint ventures			0.50%
Gain on sale of property			$ 100,000
Average adjusted capital | CCIF | Maximum
Distributions Of Available Cash and Deferred Revenue Earned
Incentive fees						2.344%
Average adjusted capital | CCIF | Minimum
Distributions Of Available Cash and Deferred Revenue Earned
Incentive fees						1.875%
Net investment income | CCIF | Minimum
Distributions Of Available Cash and Deferred Revenue Earned
Incentive fees						20.00%
Capital gain | CCIF | Minimum
Distributions Of Available Cash and Deferred Revenue Earned
Incentive fees						20.00%
Front-end fees | CCIF
Distributions Of Available Cash and Deferred Revenue Earned
Maximum personnel and overhead reimbursement, percentage				18.00%		18.00%
Gross proceeds | CCIF
Distributions Of Available Cash and Deferred Revenue Earned
Maximum personnel and overhead reimbursement, percentage				82.00%		82.00%
Gross proceeds | CESH I
Distributions Of Available Cash and Deferred Revenue Earned
Advisory fee rate						2.50%
Average net asset | CCIF
Distributions Of Available Cash and Deferred Revenue Earned
Reimbursement percentage						1.75%