Basis of Presentation (Details)	Mar. 31, 2012 Centers
Ownership Interests [Line Items]
Number Of Centers Owned Less Than 51 Percent	3
Consolidated [Member]
Ownership Interests [Line Items]
Number Of Centers Owned Less Than 51 Percent	1
Nonconsolidated [Member]
Ownership Interests [Line Items]
Number Of Centers Owned Less Than 51 Percent	2