Debt (Schedule of Estimated Net Leverage Ratio and Estimated Margin) (Details)	3 Months Ended
	Mar. 31, 2012
Debt Instrument [Line Items]
Margin increase or decrease percentage	0.25%
Amortization rate of initial principal amount per annum payable quarterly	1.00%
Credit-linked Revolving Facility [Member]
Debt Instrument [Line Items]
Estimated margin	1.50%
Estimated total net leverage ratio	1.56
Line of credit facility, unused capacity, commitment fee percentage	1.50%
Credit-linked Revolving Facility [Member] | Decreases Margin by Zero Point Twenty Five Percent [Member]
Debt Instrument [Line Items]
Net leverage ratio parameters	not applicable
Credit-linked Revolving Facility [Member] | Increases Margin by Zero Point Twenty Five Percent [Member]
Debt Instrument [Line Items]
Net leverage ratio parameters	> 2.25:1.00
Term C Loan Facility [Member]
Debt Instrument [Line Items]
Estimated margin	2.75%
Estimated total net leverage ratio	1.56
Term C Loan Facility [Member] | Decreases Margin by Zero Point Twenty Five Percent [Member]
Debt Instrument [Line Items]
Net leverage ratio parameters	< = 1.75:1.00
Term C Loan Facility [Member] | Increases Margin by Zero Point Twenty Five Percent [Member]
Debt Instrument [Line Items]
Net leverage ratio parameters	> 2.25:1.00
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Estimated margin	2.50%
Line of credit facility, unused capacity, commitment fee percentage	0.25%