Credit Agreements (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended							3 Months Ended				1 Months Ended					1 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2012 Credit agreement M denominator numerator	Dec. 31, 2012 Credit agreement After March 31, 2012	Dec. 31, 2012 Credit agreement Minimum	Dec. 31, 2012 Credit agreement Maximum	Dec. 31, 2012 Senior Secured Term Loan	Sep. 30, 2012 Senior Secured Term Loan	Dec. 31, 2012 Revolving credit facility	Dec. 31, 2012 Credit agreement - dollar-denominated loans	Dec. 31, 2012 Credit agreement - dollar-denominated loans Federal Funds rate	Dec. 31, 2012 Credit agreement - dollar-denominated loans LIBOR	Dec. 31, 2012 Senior notes	Mar. 31, 2010 8 1/4 % Senior notes due March 2017	Dec. 31, 2012 8 1/4 % Senior notes due March 2017	Sep. 30, 2012 8 1/4 % Senior notes due March 2017	Dec. 31, 2011 8 1/4 % Senior notes due March 2017	Mar. 31, 2011 8 1/4 % Senior notes due March 2017	Mar. 31, 2010 8 1/2 % Senior notes due March 2020	Dec. 31, 2012 8 1/2 % Senior notes due March 2020	Sep. 30, 2012 8 1/2 % Senior notes due March 2020	Dec. 31, 2011 8 1/2 % Senior notes due March 2020	Mar. 31, 2011 8 1/2 % Senior notes due March 2020	Dec. 31, 2012 Letter of credit
Long term debt
Long term debt	$ 955.0	$ 955.0					$ 455.0	$ 455.0							$ 250.0	$ 250.0				$ 250.0	$ 250.0
Less current maturities	(16.3)	0
Long term debt net of current maturities	938.7	955.0
Debt, current
Revolving Credit Facility	0	0
Current maturities of long-term debt	16.3	0
Revolving line of credit and current maturities of long-term debt	16.3	0
Debt instrument interest rate (as a percent)															8.25%		8.25%	8.25%		8.50%		8.50%	8.50%
Maximum borrowing capacity									525
Debt issued							455.0							250.0					250.0
Quarterly principal installment, at commencement							16.25
Payment due at maturity							341.25
Letters of credit outstanding																								176.0
Available borrowing capacity									349.0
Revolving credit facility, unused commitment fee rate (as a percent)					0.25%	0.50%
Letter of credit fees percentage on available borrowing capacity, low end of range (as a percent)																								0.75%
Letter of credit fees percentage on available borrowing capacity, high end of range (as a percent)																								1.25%
Variable rate basis			LIBOR plus a specified margin							base rate (which is the highest of (a) the administrative agent’s prime rate, (b) the federal funds rate plus 0.50% or (c) the sum of 1% plus one-month LIBOR) plus a specified margin	federal funds rate	one-month LIBOR
Interest spread in basis points (as a percent)							1.75%		1.75%		0.50%	1.00%
Weighted-average interest rate (as a percent)							1.96%
Maximum leverage ratio, numerator			4.50
Maximum leverage ratio, denominator			1
Minimum interest coverage ratio, numerator			2.50
Minimum interest coverage ratio, denominator			1
Maximum senior secured leverage ratio, numerator			2.75
Maximum senior secured leverage ratio, denominator			1.0
Period within which entity expects to be able to meet the financial covenants (in months)			12
Dividend payment restriction under credit agreement
Maximum aggregate dividends and other distributions allowed during any fiscal year			485
Percentage of consolidated net income of the Company and its subsidiaries accrued on a cummulative basis during the period beginning on April 1, 2012 and ending on the last day of the fiscal quarter			50.00%
Percentage of consolidated net deficit of the Company and its subsidiaries accrued on a cummulative basis during the period beginning on April 1, 2012 and ending on the last day of the fiscal quarter			100.00%
Percentage of aggregate net proceeds received by the Company subsequent ot March 31, 2012 as a contribution to its common equity or from the issuance and sale of its Common Stock				100.00%
Fair value of debt													$ 553