Status of Outstanding Restricted Stock Unit Awards Under Twenty Twelve Plan and Twenty Zero Two Plan (Detail) (Restricted Stock Unit Awards, USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Restricted Stock Unit Awards
NUMBER
Restricted Stock Unit Awards Outstanding, at beginning of the year	3,478,886
Granted	1,086,241
Distributed	(1,015,253)
Forfeited	(167,965)
Stock and Stock Unit Awards Outstanding, at the end of year	3,381,909
Units Convertible, at the end of year	187,010
AGGREGATE INTRINSIC VALUE
Restricted Stock Unit Awards Outstanding, at beginning of the year	$ 215.3
Stock and Stock Unit Awards Outstanding, at the end of year	227.9
Units Convertible, at the end of year	$ 12.6