Employee Benefits and Incentive Plans - Summary of Information on Options Granted under Executive Incentive Plan (Detail)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
0.00-13.12 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit	$ 0.00
Exercise Price, Upper Limit	$ 13.12
Outstanding Number of Options | shares	69,136
Outstanding Average Remaining Contractual Life (years)	11 months 5 days
Outstanding Weighted Average Exercise Price	$ 13.12
Exercisable Number of Options | shares	69,136
Exercisable Weighted Average Exercise Price	$ 13.12
13.13-28.88 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit	13.13
Exercise Price, Upper Limit	$ 28.88
Outstanding Number of Options | shares	1,694,648
Outstanding Average Remaining Contractual Life (years)	6 years 5 months 23 days
Outstanding Weighted Average Exercise Price	$ 25.10
Exercisable Number of Options | shares	994,611
Exercisable Weighted Average Exercise Price	$ 25.23
28.89-50.88 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit	28.89
Exercise Price, Upper Limit	$ 50.88
Outstanding Number of Options | shares	498,248
Outstanding Average Remaining Contractual Life (years)	5 years 6 months 26 days
Outstanding Weighted Average Exercise Price	$ 33.89
Exercisable Number of Options | shares	498,248
Exercisable Weighted Average Exercise Price	$ 33.89
50.89-84.80 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit	50.89
Exercise Price, Upper Limit	$ 84.80
Outstanding Number of Options | shares	17,998
Outstanding Average Remaining Contractual Life (years)	4 years 8 months 1 day
Outstanding Weighted Average Exercise Price	$ 77.74
Exercisable Number of Options | shares	16,434
Exercisable Weighted Average Exercise Price	$ 77.06
0.00-84.80 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit	0.00
Exercise Price, Upper Limit	$ 84.80
Outstanding Number of Options | shares	2,280,030
Outstanding Average Remaining Contractual Life (years)	6 years 1 month 6 days
Outstanding Weighted Average Exercise Price	$ 27.08
Exercisable Number of Options | shares	1,578,429
Exercisable Weighted Average Exercise Price	$ 27.98