Impairment and Other Charges - Summary of Impairment and Other Charges (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2012	Sep. 30, 2010	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Indefinite-lived Intangible Assets [Line Items]
Goodwill impairment (Note 5)				$ 0	$ 0	$ 430,101
Wireless license impairment (Note 5)				0	377	766
Property and equipment impairment (Note 2)		46,500		13,640	0	46,460
Severance and restructuring activities			14,753	25,759	0	0
Post-acquisition charges (Note 6)				0	26,393	0
Impairments and other charges				39,399	26,770	477,327
Impairments and other charges, to be settled in cash	$ 11,000			$ 12,950	$ 22,046	$ 0