Fair Value Measurements (Summary Of Fair Values, Principal Values And Carrying Values Of Debt Instruments) (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2012 Convertible Senior Notes 1.875% Due 2013 [Member]	Mar. 31, 2012 Convertible Senior Notes 4.0% Due 2014 [Member]	Mar. 31, 2012 Senior Notes 8.0% Due 2016 [Member]	Mar. 31, 2012 Senior Notes 8.25% Due 2019 [Member]	Mar. 31, 2012 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Mar. 31, 2012 Tower Securities 5.101 percentage 2010-2 [Member]	Mar. 31, 2012 Fair Value [Member] Convertible Senior Notes 1.875% Due 2013 [Member]	Dec. 31, 2011 Fair Value [Member] Convertible Senior Notes 1.875% Due 2013 [Member]	Mar. 31, 2012 Fair Value [Member] Convertible Senior Notes 4.0% Due 2014 [Member]	Dec. 31, 2011 Fair Value [Member] Convertible Senior Notes 4.0% Due 2014 [Member]	Mar. 31, 2012 Fair Value [Member] Senior Notes 8.0% Due 2016 [Member]	Dec. 31, 2011 Fair Value [Member] Senior Notes 8.0% Due 2016 [Member]	Mar. 31, 2012 Fair Value [Member] Senior Notes 8.25% Due 2019 [Member]	Dec. 31, 2011 Fair Value [Member] Senior Notes 8.25% Due 2019 [Member]	Mar. 31, 2012 Fair Value [Member] 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Dec. 31, 2011 Fair Value [Member] 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Mar. 31, 2012 Fair Value [Member] Tower Securities 5.101 percentage 2010-2 [Member]	Dec. 31, 2011 Fair Value [Member] Tower Securities 5.101 percentage 2010-2 [Member]	Mar. 31, 2012 Fair Value [Member] Revolving Credit Facility [Member]	Mar. 31, 2012 Fair Value [Member] Term Loan [Member]	Dec. 31, 2011 Fair Value [Member] Term Loan [Member]	Mar. 31, 2012 Principal Value [Member] Convertible Senior Notes 1.875% Due 2013 [Member]	Dec. 31, 2011 Principal Value [Member] Convertible Senior Notes 1.875% Due 2013 [Member]	Mar. 31, 2012 Principal Value [Member] Convertible Senior Notes 4.0% Due 2014 [Member]	Dec. 31, 2011 Principal Value [Member] Convertible Senior Notes 4.0% Due 2014 [Member]	Mar. 31, 2012 Principal Value [Member] Senior Notes 8.0% Due 2016 [Member]	Dec. 31, 2011 Principal Value [Member] Senior Notes 8.0% Due 2016 [Member]	Mar. 31, 2012 Principal Value [Member] Senior Notes 8.25% Due 2019 [Member]	Dec. 31, 2011 Principal Value [Member] Senior Notes 8.25% Due 2019 [Member]	Mar. 31, 2012 Principal Value [Member] 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Dec. 31, 2011 Principal Value [Member] 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Mar. 31, 2012 Principal Value [Member] Tower Securities 5.101 percentage 2010-2 [Member]	Dec. 31, 2011 Principal Value [Member] Tower Securities 5.101 percentage 2010-2 [Member]	Mar. 31, 2012 Principal Value [Member] Revolving Credit Facility [Member]	Mar. 31, 2012 Principal Value [Member] Term Loan [Member]	Dec. 31, 2011 Principal Value [Member] Term Loan [Member]	Mar. 31, 2012 Carrying Value [Member] Convertible Senior Notes 1.875% Due 2013 [Member]	Dec. 31, 2011 Carrying Value [Member] Convertible Senior Notes 1.875% Due 2013 [Member]	Mar. 31, 2012 Carrying Value [Member] Convertible Senior Notes 4.0% Due 2014 [Member]	Dec. 31, 2011 Carrying Value [Member] Convertible Senior Notes 4.0% Due 2014 [Member]	Mar. 31, 2012 Carrying Value [Member] Senior Notes 8.0% Due 2016 [Member]	Dec. 31, 2011 Carrying Value [Member] Senior Notes 8.0% Due 2016 [Member]	Mar. 31, 2012 Carrying Value [Member] Senior Notes 8.25% Due 2019 [Member]	Dec. 31, 2011 Carrying Value [Member] Senior Notes 8.25% Due 2019 [Member]	Mar. 31, 2012 Carrying Value [Member] 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Dec. 31, 2011 Carrying Value [Member] 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Mar. 31, 2012 Carrying Value [Member] Tower Securities 5.101 percentage 2010-2 [Member]	Dec. 31, 2011 Carrying Value [Member] Tower Securities 5.101 percentage 2010-2 [Member]	Mar. 31, 2012 Carrying Value [Member] Revolving Credit Facility [Member]	Mar. 31, 2012 Carrying Value [Member] Term Loan [Member]	Dec. 31, 2011 Carrying Value [Member] Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument							$ 673.8	$ 605.2	$ 880.3	$ 761.6	$ 403.1	$ 405.0	$ 413.9	$ 407.8	$ 708.4	$ 699.0	$ 594.4	$ 579.0	$ 200.0	$ 495.0	$ 494.4	$ 535.0	$ 535.0	$ 500.0	$ 500.0	$ 375.0	$ 375.0	$ 375.0	$ 375.0	$ 680.0	$ 680.0	$ 550.0	$ 550.0	$ 200.0	$ 496.3	$ 497.5	$ 493.9	$ 485.0	$ 405.5	$ 397.6	$ 373.3	$ 373.2	$ 372.4	$ 372.4	$ 680.0	$ 680.0	$ 550.0	$ 550.0	$ 200.0	$ 495.1	$ 496.3
Interest rate for senior notes	1.875%	4.00%	8.00%	8.25%	4.254%	5.101%
Convertible senior notes, maturity date	2013	2014
Maturity date			2016	2019