Property Transactions Property Transactions (Held for Sale) (Details) $ in Millions	3 Months Ended
Mar. 31, 2016 USD ($) ft²
Long Lived Assets Held-for-sale [Line Items]
Area of Real Estate Property \| ft²	129,000
Proceeds from Sale of Property Held-for-sale \| $	$ 22.0

The cash inflow from the sale of formerly productive land held for sale, anything permanently fixed to it, including buildings, structures on it, and so forth.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromSaleOfPropertyHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration