Credit Facilities (Detail) (USD $)	3 Months Ended	6 Months Ended	9 Months Ended	0 Months Ended		2 Months Ended	12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014 Financial_Institutions	Sep. 30, 2014	Oct. 01, 2014	Jun. 06, 2014	Feb. 28, 2013	Feb. 28, 2014	Dec. 31, 2013		Sep. 30, 2013	Nov. 12, 2014	Dec. 23, 2013	Jan. 03, 2014	Nov. 05, 2013
Line of Credit Facility [Line Items]
Credit facilities	$ 4,259,000,000		$ 4,259,000,000					$ 1,969,800,000	[1]	$ 1,310,000,000
Credit facility, undrawn commitment	60,000,000		60,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member]
Line of Credit Facility [Line Items]
Number of financial institutions		20
Credit facility, current borrowing capacity	4,700,000,000		4,700,000,000
Credit facilities	4,300,000,000		4,300,000,000
Credit facility, maximum borrowing capacity		6,000,000,000
Credit facility, increase (decrease), net	50,000,000
Credit facility, length of extension option			1 year
Write off of unamortized (premium) discount		3,900,000
Credit facility, undrawn commitment	391,000,000		391,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Credit facility, current borrowing capacity		4,650,000,000									4,000,000,000	3,600,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Term Loan Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, current borrowing capacity		1,200,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Term Loan Facility [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Interest rate, stated percentage	1.60%		1.60%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Term Loan Facility, Delayed Draw Component [Member]
Line of Credit Facility [Line Items]
Credit facility, current borrowing capacity		200,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Line of Credit, Variable Interest Rate [Member]
Line of Credit Facility [Line Items]
Credit facilities	3,300,000,000		3,300,000,000
Interest rate, stated percentage	1.50%		1.50%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Revolving Credit Facility, Multi-Currency Denominated [Member]
Line of Credit Facility [Line Items]
Credit facility, current borrowing capacity		250,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Repayments of revolving credit facility				1,210,000,000
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Revolving Credit Facility [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Interest rate, stated percentage	1.35%		1.35%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Revolving Credit Facility [Member] | Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Line of Credit, Fixed Interest Rate [Member]
Line of Credit Facility [Line Items]
Credit facilities	1,000,000,000		1,000,000,000
Line of credit, amount bearing fixed interest rate, percentage	2.84%		2.84%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Credit facility, commitment fee percentage			0.15%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Minimum [Member] | Term Loan Facility [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.15%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Minimum [Member] | Term Loan Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.15%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Minimum [Member] | Revolving Credit Facility [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Minimum [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.00%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Credit facility, commitment fee percentage			0.25%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Maximum [Member] | Term Loan Facility [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			2.05%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Maximum [Member] | Term Loan Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.05%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Maximum [Member] | Revolving Credit Facility [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.80%
Senior Secured Credit Facility [Member] | Senior Corporate Credit Facility [Member] | Maximum [Member] | Revolving Credit Facility [Member] | Base Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.80%
Senior Secured Credit Facility [Member] | Regions Bank Unsecured Credit Facility [Member] | ARCT IV [Member]
Line of Credit Facility [Line Items]
Credit facility, current borrowing capacity													800,000,000
Credit facilities													760,000,000
Senior Secured Credit Facility [Member] | Regions Bank Unsecured Credit Facility [Member] | Term Loan Facility [Member] | ARCT IV [Member]
Line of Credit Facility [Line Items]
Credit facilities													300,000,000
Senior Secured Credit Facility [Member] | Regions Bank Unsecured Credit Facility [Member] | Revolving Credit Facility [Member] | ARCT IV [Member]
Line of Credit Facility [Line Items]
Credit facilities													460,000,000
Senior Secured Credit Facility [Member] | Unsecured Credit Facility [Member] | CapLease [Member]
Line of Credit Facility [Line Items]
Credit facility, current borrowing capacity														150,000,000
Extinguishment of debt, amount					150,000,000
Senior Secured Credit Facility [Member] | Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Extinguishment of debt, amount							$ 124,600,000
Effective interest rate						3.11%

[1] For discussion on the restatement adjustments, see Note 2 - Restatement of Previously Issued Consolidated Financial Statements.