Status of Outstanding Restricted Stock Unit Awards Under Twenty Twelve Plan and Twenty Zero Two Plan (Detail) - Restricted Stock Unit Awards $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) shares
NUMBER
Restricted Stock Unit Awards Outstanding, at beginning of the year (in shares)	3,402,970
Granted (in shares)	1,301,693
Distributed (in shares)	(923,776)
Forfeited (in shares)	(85,230)
Stock and Stock Unit Awards Outstanding, at the end of year (in shares)	3,695,657
Units Convertible, at the end of year (in shares)	180,025
AGGREGATE INTRINSIC VALUE
Restricted Stock Unit Awards Outstanding, at beginning of the year | $	$ 245.3
Stock and Stock Unit Awards Outstanding, at the end of year | $	329.1
Units Convertible, at the end of year | $	$ 16.0