Restricted Stock Units - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended				24 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Jan. 01, 2015
Share Based Payments Disclosure [Line Items]
Description of vesting term for awards granted	Awards granted under the plan generally vest ratably over a period of five years beginning on the first anniversary of the grant date or in full on the fifth anniversary of the grant date.
Stock units granted at closing, ratable vesting period	5 years
Fair value of restricted stock units settled in cash				$ 11.0
Restricted stock unit settled in cash, cash paid			2.1	8.9
Restricted Stock Units
Share Based Payments Disclosure [Line Items]
Granted	1,395,346	[1]	1,070,762
Restricted stock units outstanding	3,260,586		2,718,950	2,813,567
Compensation expense from the vesting of restricted stock units	54.2		52.8	53.6
Weighted average grant date fair value for restricted stock units granted	$ 47.72		$ 72.75	$ 78.19
Unrecognized restricted stock units compensation expense	$ 85.0
Unrecognized restricted stock units compensation expense, weighted average recognition period					1 year 9 months 18 days
Settled in Cash | Restricted Stock Units
Share Based Payments Disclosure [Line Items]
Restricted stock units settled in cash				141,960

[1] Excludes 1,011,665 stock units granted to employees subsequent to December 31, 2012 as part of the long term incentive awards program.