Restructuring - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended			36 Months Ended	1 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Jul. 31, 2012 Areas Employees	Aug. 31, 2014 Employees
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring charges related to employee severance and benefit costs			$ 7
Pre-tax restructuring charges	67	82	18	67
Employee severance and benefit costs from restructurings beginning in 2012					133
Employee severance and benefit cost payments through the balance sheet date					94
Remaining employee severance payable through our restructuring efforts		33
Completion date of restructuring activities					Dec. 31, 2015
2012 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Number of employee positions eliminated						700
Pre-tax restructuring charges related to employee severance and benefit costs				56
Pre-tax restructuring charges				67
Number of areas pre restructuring						22
Number of areas post restructuring						17
Two Thousand Fourteen Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Number of employee positions eliminated							650
Pre-tax restructuring charges related to employee severance and benefit costs		70
Pre-tax restructuring charges		82
2013 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring charges			$ 18