Debt Table (Details) In Millions, unless otherwise specified	Mar. 31, 2012 USD ($)		Dec. 31, 2011 USD ($)		Jun. 30, 2007 USD ($)	Mar. 31, 2012 Senior Notes [Member] $850 million 6.375% Senior Notes due 2012 USD ($)	Dec. 31, 2011 Senior Notes [Member] $850 million 6.375% Senior Notes due 2012 USD ($)	Mar. 31, 2012 Senior Notes [Member] Canadian dollar ("CAD") 900 million 5.0% notes due 2015 USD ($)	Dec. 31, 2011 Senior Notes [Member] Canadian dollar ("CAD") 900 million 5.0% notes due 2015 USD ($)	Mar. 31, 2012 Senior Notes [Member] $575 million 2.5% convertible Senior Notes due 2013 USD ($)		Dec. 31, 2011 Senior Notes [Member] $575 million 2.5% convertible Senior Notes due 2013 USD ($)		Jun. 25, 2011 Senior Notes [Member] $575 million 2.5% convertible Senior Notes due 2013 USD ($)	Mar. 31, 2012 Senior Notes [Member] CAD 500 million 3.95% Series A notes due 2017 USD ($)	Dec. 31, 2011 Senior Notes [Member] CAD 500 million 3.95% Series A notes due 2017 USD ($)	Oct. 06, 2010 Senior Notes [Member] CAD 500 million 3.95% Series A notes due 2017 CAD	Mar. 31, 2012 Convertible Debt [Member] Fair Value, Inputs, Level 1 [Member] USD ($)	Dec. 31, 2011 Convertible Debt [Member] Fair Value, Inputs, Level 1 [Member] USD ($)	Mar. 31, 2012 Other Debt Obligations [Member] Fair Value, Inputs, Level 2 [Member] USD ($)	Dec. 31, 2011 Other Debt Obligations [Member] Fair Value, Inputs, Level 2 [Member] USD ($)
Debt Instrument [Line Items]
Total long-term debt (including current portion) before unamortized discounts and other						$ 44.6	$ 44.6	$ 901.2	$ 881.2	$ 575.0	[1],[2]	$ 575.0	[1],[2]		$ 500.7	$ 489.6
Less: unamortized debt discounts and other	(26.5)	[2]	(30.8)	[2]
Total long-term debt (including current portion)	1,995.0		1,959.6
Less: current portion of long-term debt	(44.6)		(44.7)
Total long-term debt	1,950.4		1,914.9
Total fair value	2,126.1		2,133.6															603.2	608.5	1,522.9	1,525.1
Debt Instrument, Face Amount					$ 575	$ 850		$ 900						$ 575	$ 500		500
Debt Instrument, Interest Rate, Stated Percentage						6.375%		5.00%		2.50%					3.95%		3.95%

[1] The original conversion price for each $1,000 aggregate principal amount of notes was $54.76 per share of our Class B common stock, which represented a 25% premium above the stock price on the day of issuance of the notes and corresponded to the initial conversion ratio of 18.263 shares per each $1,000 aggregate principal amount of notes. The conversion ratio and conversion price are subject to adjustments for certain events and provisions, as defined in the indenture. As of March 2012, our conversion price and ratio are $52.79 and 18.9441 shares, respectively. Currently, the convertible debt's if-converted value does not exceed the principal.

[2] During the first quarters of 2012 and 2011, we incurred additional non-cash interest expense of $4.5 million and $4.3 million, respectively. We also incurred interest expense related to the 2.5% convertible coupon rate of $3.7 million during the first quarter of 2012, and $3.6 million during the first quarter of 2011. The combination of non-cash and cash interest resulted in an effective interest rate of 5.91% and 5.97% for the first quarters of 2012 and 2011, respectively. In relation to this issuance, paid in capital in the equity section of our balance sheet includes $103.9 million, ($64.2 million net of tax), representing the equity component of the convertible debt. Further, as of March 31, 2012, and December 31, 2011, $24.4 million and $28.9 million, respectively, of the unamortized debt discount and other balance relates to our $575 million convertible debt. We expect to record additional non-cash interest expense of approximately $14 million in 2012 and $11 million in 2013, thereby increasing the carrying value of the convertible debt to its $575 million face value at maturity in July 2013. The remaining $2.1 million and $1.9 million as of March 31, 2012, and December 31, 2011, respectively, relates to unamortized debt premiums, discounts, and other on the additional debt balances.