Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

Our financial assets and liabilities that are measured at fair value on a recurring basis are as follows (in millions):

			Fair Value Measurements at Reporting Date Using
As of December 31, 2013	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Valuation Technique (1)
Prepaid expenses and other current assets:
Current portion of restricted marketable securities	$	4.7	$	—	$	4.7	$	—	M
Other long-term assets:
Restricted marketable securities	42.9		—		42.9		—		M
As of December 31, 2012
Prepaid expenses and other current assets:
Current portion of restricted marketable securities	$	16.4	$	—	$	16.4	$	—	M
Other long-term assets:
Restricted marketable securities	39.4		—		39.4		—		M

⁽¹⁾  The three valuation techniques are: market approach (M), cost approach (C), and income approach (I).

Schedule of Carrying Amounts and Estimated Fair Values, Financial Instruments

The carrying amounts and estimated fair values for our other financial instruments are presented in the following table (in millions): 

	As of December 31, 2013				As of December 31, 2012
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Long-term debt:
Advances under revolving credit facility	$	45.0	$	45.0	$	—	$	—
7.25% Senior Notes due 2018	272.4		291.4		302.9		328.6
8.125% Senior Notes due 2020	286.6		319.4		286.2		321.5
7.75% Senior Notes due 2022	252.5		275.0		280.7		306.5
5.75% Senior Notes due 2024	275.0		273.6		275.0		277.1
2.00% Convertible Senior Subordinated Notes due 2043	249.5		339.7		—		—
Other notes payable	47.6		47.6		36.8		36.8
Financial commitments:
Letters of credit	—		36.5		—		39.5