Debt (Senior Secured Credit Facilities) (Details)	1 Months Ended		3 Months Ended								12 Months Ended
	Jan. 31, 2017 USD ($)	Oct. 31, 2014 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Loss on extinguishment of debt			$ 22,000,000	$ 0	$ 112,000,000	$ 0	$ 0	$ 0	$ 0	$ (13,000,000)	$ 134,000,000	$ 13,000,000	$ 0
Aggregate principal amount (more than)		$ 100,000,000
ABL Revolver [Member]
Line of Credit Facility [Line Items]
Debt term		5 years
Current borrowing capacity		$ 1,200,000,000.0	1,000,000,000.0								$ 1,000,000,000.0
Potential additional borrowing capacity		$ 500,000,000
Debt covenant, minimum fixed charge coverage ratio		1.25
Covenant, minimum amount for excess availability under ABL Revolver		$ 110,000,000
Covenant, percentage applied on lesser of ABL Revolver commitment and applicable borrowing base		12.50%
Number of days preceding maturity date		90 days
Percentage of the lesser of total revolver commitment to applicable borrowing base		20.00%
ABL Revolver [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Percentage of the lesser of total revolver commitment to applicable borrowing base		25.00%
ABL Revolver [Member] | LIBOR [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.50%
ABL Revolver [Member] | LIBOR [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate		2.00%
ABL Revolver [Member] | Prime Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
ABL Revolver [Member] | Prime Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
Secured Debt [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Covenant, Minimum Senior Net Leverage Ratio											3.50
ABL Facility [Member] | Seven-year Secured Term Loan Credit Facility [Member]
Line of Credit Facility [Line Items]
Principal amount			1,800,000,000.0								$ 1,800,000,000.0
Debt term											5 years
Long-term debt, current			18,000,000								$ 18,000,000
Subordinated Lien Revolver [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Principal amount						$ 150,000,000				$ 200,000,000
ABL Revolver [Member]
Line of Credit Facility [Line Items]
Debt term											5 years
Current borrowing capacity			1,000,000,000.0								$ 1,000,000,000.0
Term Loan Credit Agreement, Due June 2, 2022 [Member] | Secured Debt [Member]
Line of Credit Facility [Line Items]
Principal amount	$ 1,800,000,000.0
Debt Instrument, Quarterly Amortization Payment, Percentage	0.25%
Debt Instrument, Covenant, Minimum Senior Net Leverage Ratio	3.00					1.00
Debt Instrument, Prepayment Premium, Percentage	1.00%
Term Loan Credit Agreement, Due June 2, 2022 [Member] | Secured Debt [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Potential additional borrowing capacity	$ 300,000,000
Term Loan Credit Agreement, Due June 2, 2022 [Member] | Secured Debt [Member] | LIBOR [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.85%
Debt Issuance Costs Incurred [Member]
Line of Credit Facility [Line Items]
Long-term debt, principal			$ 56,000,000	45,000,000							$ 56,000,000
Debt Issuance Costs Paid [Member]
Line of Credit Facility [Line Items]
Long-term debt, principal				$ 52,000,000