Equity Total Comprehensive Income, Equity and their Components (Parenthetical) (Details) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Stockholders Equity Note [Line Items]
Dividends on noncontrolling interest units	$ 0.6950	$ 0.6600

Per-share or per-unit cash distributions declared to a common shareholder or unit-holder by an LLC or LP.

No definition available.

Name:	us-gaap_DistributionMadeToMemberOrLimitedPartnerDistributionsDeclaredPerUnit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration