Restructuring Charges- Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended	36 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2011 position	Dec. 31, 2014	Apr. 01, 2014
Streamlining Actions
Restructuring Cost and Reserve [Line Items]
Net additional charges (net recovery/gain)	$ (2)	$ 6
Restructuring reserve	65	92		92	125
Operational Efficiency Initiatives 2011
Restructuring Cost and Reserve [Line Items]
Net additional charges (net recovery/gain)	(2)	(6)		36
Restructuring reserve	22	28	107	28
Estimated reduction in workforce due to restructuring (positions)			1,500
Severance
Restructuring Cost and Reserve [Line Items]
Net additional charges (net recovery/gain)	(4)
Severance | Operational Efficiency Initiatives 2011
Restructuring Cost and Reserve [Line Items]
Net additional charges (net recovery/gain)	(2)			93
Restructuring reserve	22	28	78	28
Other | Operational Efficiency Initiatives 2011
Restructuring Cost and Reserve [Line Items]
Net additional charges (net recovery/gain)	0			(57)
Restructuring reserve	$ 0	$ 0	$ 29	$ 0