Derivative Instruments (Details 1) (Parenthetical)	Mar. 31, 2013
Minimum
Derivatives Fair Value [Line Items]
Spread ranging	0.75%
Maximum
Derivatives Fair Value [Line Items]
Spread ranging	2.75%

The average percentage points added to the reference rate to compute the variable rate on the group of interest rate derivatives.

No definition available.

Name:	us-gaap_DerivativeAverageBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant