Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Subsequent Event [Line Items]
Acres of land committed to purchase	6
Square Footage of Real Estate Property	157,000
Land [Member]
Subsequent Event [Line Items]
Unrecorded Purchase Commitment, Property	2.0
Building [Member]
Subsequent Event [Line Items]
Unrecorded Purchase Commitment, Property	11.1