Credit Facilities (Details) (USD $)			6 Months Ended					6 Months Ended						6 Months Ended													0 Months Ended	2 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] financial_institution	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Minimum [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Maximum [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility [Member] LIBOR [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility [Member] Minimum [Member] LIBOR [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility [Member] Minimum [Member] Base Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility [Member] Maximum [Member] LIBOR [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility [Member] Maximum [Member] Base Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Term Loan Facility, Delayed Draw Component [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility [Member] LIBOR [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility [Member] Federal Funds Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility [Member] Minimum [Member] LIBOR [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility [Member] Minimum [Member] Base Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility [Member] Maximum [Member] LIBOR [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility [Member] Maximum [Member] Base Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility, Dollar Denominated [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Revolving Credit Facility, Multi-Currency Denominated [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Line of Credit, Variable Interest Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Senior Corporate Credit Facility [Member] Line of Credit, Fixed Interest Rate [Member]	Jun. 30, 2014 Line of Credit [Member] Regions Bank Unsecured Credit Facility [Member] ARCT IV [Member]	Jun. 30, 2014 Line of Credit [Member] Regions Bank Unsecured Credit Facility [Member] Term Loan Facility [Member] ARCT IV [Member]	Jun. 30, 2014 Line of Credit [Member] Regions Bank Unsecured Credit Facility [Member] Revolving Credit Facility [Member] ARCT IV [Member]	Jun. 30, 2014 Line of Credit [Member] Unsecured Credit Facility [Member] CapLease [Member]	Jun. 06, 2014 Line of Credit [Member] Unsecured Credit Facility [Member] CapLease [Member]	Feb. 28, 2013 Line of Credit [Member] Senior Secured Revolving Credit Facility [Member] Revolving Credit Facility [Member]	Feb. 28, 2014 Line of Credit [Member] Senior Secured Revolving Credit Facility [Member] Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Number of financial institutions			20
Line of credit facility, current borrowing capacity			$ 4,600,000,000.0			$ 1,200,000,000						$ 200,000,000							$ 3,150,000,000	$ 250,000,000			$ 800,000,000			$ 150,000,000
Line of credit facility, maximum borrowing capacity			6,000,000,000
Debt instrument, basis spread on variable rate								1.15%	0.15%	2.05%	1.05%			0.50%	1.00%	0.00%	1.80%	0.80%
Debt instrument, interest rate, stated percentage							1.60%						1.35%								1.50%
Line of credit facility, length of extension option			1 year
Line of credit facility, commitment fee percentage				0.15%	0.25%
Write off of deferred debt issuance cost			3,900,000
Credit facilities	1,896,000,000	1,969,800,000	1,900,000,000																		881,000,000	1,000,000,000	760,000,000	300,000,000	460,000,000
Line of credit, amount bearing fixed interest rate, percentage																						2.84%
Line of credit facility, undrawn commitment			2,700,000,000
Extinguishment of debt, amount																											$ 150,000,000		$ 124,600,000
Effective interest rate																												3.11%