Basis of Presentation and Summary of Significant Accounting Policies (Details 4) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended					3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2012 Minimum	Dec. 31, 2012 Maximum	Dec. 31, 2012 Customer relationships	Dec. 31, 2012 Capitalized software Maximum	Mar. 31, 2011 Predecessor	Dec. 31, 2010 Predecessor	Dec. 31, 2012 Trade names and trademark
Revenue Recognition
Customer relationship period over which revenue is recognized			18 months	10 years
Term of IRUs		20 years
Affiliates Transactions
Noncash dividends recognized	$ 28
Advertising Costs
Advertising expense	174	90					65	292
Income Taxes
Valuation allowance on deferred tax assets	8	12
Accounts Receivable and Allowance for Doubtful Accounts
Period of accounts past due			30 days
Property, Plant and Equipment
Asset retirement obligation	$ 22	$ 21
Goodwill, Customer Relationships and Other Intangible Assets
Estimated life					10 years	7 years			4 years
Number of reporting units		1
Number of operating segments		1