Employee Retirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Matching contributions for 401(k) plan and Top Hat savings plan	$ 4	$ 3
Pension Contributions	5
Qualified Pension Plans [Member] | Future Period [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contribution by employer for the remainder of the year	$ 0