Background (Details) (USD $) In Billions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Nature of Business [Line Items]
Total Market Capitalization	$ 9.3
Total Rentable Square Footage of Asset Base	31,378,329
Area of Real Estate Property	17,881,108
Square Footage of Real Estate Property, Future Development	13,497,221
Investment-grade client tenants as a percentage of total annualized base rent	52.00%
Percentage of leases containing effective annual rent escalations	96.00%
Percentage of leases which are triple net leases	94.00%
Percentage of leases providing for recapture of certain capital expenditures	93.00%
Minimum
Nature of Business [Line Items]
Effective annual rent escalations (as a percent)	3.00%
Maximum
Nature of Business [Line Items]
Effective annual rent escalations (as a percent)	3.50%