Installment Receivables (Activity in the Deferred Interest and Allowance for Credit Losses for the Installment Receivables) (Details) (Successor [Member], Financing Receivable [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2012
Successor [Member] | Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Deferred interest and allowance for credit losses, beginning of period	$ 124	$ 329	$ 13	$ 0
Bad debt expense	44	398	3
Write-offs, net of recoveries	0	(255)	0
Change in deferred interest on short-term and long-term installment receivables	$ 67	$ 62	$ 10