Income Taxes (Income Tax (Expense) Benefit Allocated to Other Items) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended				3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2014		Mar. 31, 2015		Dec. 31, 2013		Mar. 31, 2013		Jul. 10, 2013		Dec. 31, 2012
Successor [Member]
Income Tax Contingency [Line Items]
Unrecognized net periodic pension and other postretirement benefit cost	$ 0	[1]	$ 0	[1]	$ (58)	[1]
Unrealized holding gains/losses on securities	(1)	[1]	0	[1]	(3)	[1]
Predecessor [Member]
Income Tax Contingency [Line Items]
Unrecognized net periodic pension and other postretirement benefit cost							(10)	[1]	(18)	[1]	0	[1]
Unrealized holding gains/losses on securities							$ (1)	[1]	$ 0	[1]	$ 0	[1]

[1] (1)These amounts have been recognized in accumulated other comprehensive loss.