Basis of Presentation and Summary of Significant Accounting Policies (Details 3) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended						3 Months Ended
	Dec. 31, 2011	Dec. 31, 2013 segment	Dec. 31, 2012	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Dec. 31, 2013 Customer relationships	Dec. 31, 2013 Capitalized software Maximum	Mar. 31, 2011 Predecessor
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	$ 0	$ 0					$ 0
Advertising Costs
Advertising expense	$ 174	$ 88	$ 90					$ 65
Accounts Receivable and Allowance for Doubtful Accounts
Period of accounts past due				30 days
Goodwill, Customer Relationships and Other Intangible Assets
Weighted Average of Remaining Lives						10 years	7 years
Number of reporting units (segment)		1