Credit Facility (Details) (USD $)									6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Credit facility	Dec. 31, 2013 Credit facility	Mar. 30, 2012 Credit facility	Jun. 30, 2014 Credit facility LIBOR	Aug. 20, 2013 Credit Facility	Aug. 20, 2013 Credit Facility Maximum	Jun. 30, 2014 Below Threshold Credit facility LIBOR	Jun. 30, 2014 Above Threshold Credit facility LIBOR	Jun. 30, 2014 Line of Credit Facility, Interest Rate, Option One Credit facility Maximum LIBOR	Jun. 30, 2014 Line of Credit Facility, Interest Rate, Option One Credit facility Minimum LIBOR	Jun. 30, 2014 Line of Credit Facility, Interest Rate, Option Two Credit facility Maximum Base Rate	Jun. 30, 2014 Line of Credit Facility, Interest Rate, Option Two Credit facility Minimum Base Rate	Jun. 30, 2014 Line of Credit Facility, Base Rate, Option Two Credit facility Federal Funds Effective Rate	Jun. 30, 2014 Line of Credit Facility, Base Rate, Option Three Credit facility One-Month LIBOR	Dec. 23, 2013 Term Loan Credit facility	Aug. 20, 2013 Term Loan Credit facility	Dec. 23, 2013 Credit facility	Aug. 20, 2013 Credit facility	Apr. 14, 2014 Operating Partnership Unit	Apr. 14, 2014 Operating Partnership Unit Line of Credit	Apr. 14, 2014 Operating Partnership Unit Credit facility
Line of Credit Facility [Line Items]
Maximum capacity on credit facility					$ 40,000,000.0		$ 220,000,000										$ 340,000,000	$ 110,000,000	$ 50,000,000	$ 110,000,000	$ 705,000,000	$ 400,000,000	$ 305,000,000
Accordion feature of credit facility								325,000,000
Additional borrowing capacity under certain circumstances																					1,000,000,000
Spread on variable rate basis											2.25%	1.50%	1.25%	0.50%	0.50%	1.00%
Unused capacity fee percentage									0.20%	0.30%
Credit facility	305,000,000	305,000,000	305,000,000	305,000,000
Effective interest rate			2.11%	2.19%
Unused capacity commitment fee percentage threshold						50.00%
Remaining borrowing capacity			$ 107,300,000