Supplemental Guarantor Information (Income Statement) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Supplemental guarantor information statements of operation
Net sales	$ 2,789	$ 2,847	$ 2,831	$ 2,680	$ 2,549	$ 2,403	$ 2,414	$ 2,401	$ 11,147	$ 9,767	$ 9,812
Cost of goods sold (exclusive of depreciation and amortization)	2,483	2,498	2,483	2,329	2,203	2,093	2,074	2,098	9,793	8,468	8,477
Selling, general and administrative expenses	108	108	103	108	117	115	109	120	427	461	398
Depreciation and amortization	86	87	90	89	87	91	79	77	352	334	292
Research and development expenses	12	14	12	12	11	12	12	10	50	45	46
Interest expense and amortization of debt issuance costs	78	85	82	81	77	76	75	76	326	304	298
Gain (loss) on assets held for sale	1	(12)	0	(11)	0	(6)	0	0	(22)	(6)	(3)
Loss on extinguishment of debt									0	0	7
Restructuring and impairment, net	(1)	25	7	6	29	19	18	9	37	75	47
Equity in net loss of non-consolidated affiliates	1	2	0	2	0	5	3	4	5	12	16
Equity in net (income) loss of consolidated subsidiaries									0	0	0
Other income, net	3	(9)	18	5	(14)	(12)	(5)	(10)	17	(41)	(52)
Total expenses									10,985	9,652	9,526
Income before income taxes									162	115	286
Income tax provision (benefit)	(11)	3	(2)	24	(15)	(3)	26	3	14	11	83
Net income	29	46	38	35	54	13	23	14	148	104	203
Net income attributable to noncontrolling interests	0	0	0	0	0	0	0	0	0	0	1
Net income attributable to our common shareholder	29	46	38	35	54	13	23	14	148	104	202
Comprehensive (loss) income									(337)	279	126
Less: Comprehensive loss attributable to noncontrolling interest									(15)	(2)	1
Comprehensive (loss) income attributable to our common shareholder									(322)	281	125
Parent [Member]
Supplemental guarantor information statements of operation
Net sales									665	693	781
Cost of goods sold (exclusive of depreciation and amortization)									650	677	740
Selling, general and administrative expenses									6	48	(19)
Depreciation and amortization									18	16	14
Research and development expenses									0	1	7
Interest expense and amortization of debt issuance costs									319	315	320
Gain (loss) on assets held for sale									(5)	0	(5)
Loss on extinguishment of debt											7
Restructuring and impairment, net									1	8	12
Equity in net loss of non-consolidated affiliates									0	0	0
Equity in net (income) loss of consolidated subsidiaries									(456)	(448)	(455)
Other income, net									(18)	(35)	(49)
Total expenses									515	582	572
Income before income taxes									150	111	209
Income tax provision (benefit)									2	7	7
Net income									148	104	202
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to our common shareholder									148	104	202
Comprehensive (loss) income									(322)	281	125
Less: Comprehensive loss attributable to noncontrolling interest									0	0	0
Comprehensive (loss) income attributable to our common shareholder									(322)	281	125
Guarantors [Member]
Supplemental guarantor information statements of operation
Net sales									9,525	8,080	8,076
Cost of goods sold (exclusive of depreciation and amortization)									8,413	7,055	7,028
Selling, general and administrative expenses									344	338	341
Depreciation and amortization									258	246	220
Research and development expenses									49	43	39
Interest expense and amortization of debt issuance costs									74	28	16
Gain (loss) on assets held for sale									(17)	(6)	2
Loss on extinguishment of debt											0
Restructuring and impairment, net									33	59	33
Equity in net loss of non-consolidated affiliates									5	12	16
Equity in net (income) loss of consolidated subsidiaries									(30)	(99)	(89)
Other income, net									(46)	(57)	(49)
Total expenses									9,083	7,619	7,557
Income before income taxes									442	461	519
Income tax provision (benefit)									(8)	16	57
Net income									450	445	462
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to our common shareholder									450	445	462
Comprehensive (loss) income									30	590	364
Less: Comprehensive loss attributable to noncontrolling interest									0	0	0
Comprehensive (loss) income attributable to our common shareholder									30	590	364
Non-Guarantors [Member]
Supplemental guarantor information statements of operation
Net sales									2,743	2,416	2,440
Cost of goods sold (exclusive of depreciation and amortization)									2,514	2,158	2,194
Selling, general and administrative expenses									77	75	76
Depreciation and amortization									76	72	58
Research and development expenses									1	1	0
Interest expense and amortization of debt issuance costs									7	1	(3)
Gain (loss) on assets held for sale									0	0	0
Loss on extinguishment of debt											0
Restructuring and impairment, net									3	8	2
Equity in net loss of non-consolidated affiliates									0	0	0
Equity in net (income) loss of consolidated subsidiaries									0	0	0
Other income, net									7	11	11
Total expenses									2,685	2,326	2,338
Income before income taxes									58	90	102
Income tax provision (benefit)									20	(12)	19
Net income									38	102	83
Net income attributable to noncontrolling interests									0	0	1
Net income attributable to our common shareholder									38	102	82
Comprehensive (loss) income									(7)	152	85
Less: Comprehensive loss attributable to noncontrolling interest									(15)	(2)	1
Comprehensive (loss) income attributable to our common shareholder									8	154	84
Eliminations [Member]
Supplemental guarantor information statements of operation
Net sales									(1,786)	(1,422)	(1,485)
Cost of goods sold (exclusive of depreciation and amortization)									(1,784)	(1,422)	(1,485)
Selling, general and administrative expenses									0	0	0
Depreciation and amortization									0	0	0
Research and development expenses									0	0	0
Interest expense and amortization of debt issuance costs									(74)	(40)	(35)
Gain (loss) on assets held for sale									0	0	0
Loss on extinguishment of debt											0
Restructuring and impairment, net									0	0	0
Equity in net loss of non-consolidated affiliates									0	0	0
Equity in net (income) loss of consolidated subsidiaries									486	547	544
Other income, net									74	40	35
Total expenses									(1,298)	(875)	(941)
Income before income taxes									(488)	(547)	(544)
Income tax provision (benefit)									0	0	0
Net income									(488)	(547)	(544)
Net income attributable to noncontrolling interests									0	0	0
Net income attributable to our common shareholder									(488)	(547)	(544)
Comprehensive (loss) income									(38)	(744)	(448)
Less: Comprehensive loss attributable to noncontrolling interest									0	0	0
Comprehensive (loss) income attributable to our common shareholder									$ (38)	$ (744)	$ (448)