Stock-Based Compensation - Summary of Stock Options (Detail) - Stock Options [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding shares, beginning of year | shares	8,378
Granted, shares | shares	1,455
Exercised, shares | shares	(2,170)
Forfeited or expired, shares | shares	(156)
Outstanding shares, end of year | shares	7,507
Exercisable shares, end of year | shares	3,940
Outstanding, Weighted Average Exercise Price, beginning of year | $ / shares	$ 37.22
Granted, Weighted Average Exercise Price | $ / shares	54.45
Exercised, Weighted Average Exercise Price | $ / shares	36.26
Forfeited or expired, Weighted Average Exercise Price | $ / shares	38.98
Outstanding, Weighted Average Exercise Price, end of year | $ / shares	40.80
Exercisable, Weighted Average Exercise Price, end of year | $ / shares	$ 36.44