Employee Benefits - Summary of Company's SARs Activity (Detail) - Cash-Settled Stock Appreciation Rights $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance, beginning of year, Number of SARs (shares) | shares	1,068,001
Granted, Number of SARs (shares) | shares	195,000
Exercised, Number of SARs (shares) | shares	(32,933)
Forfeited, Number of SARs (shares) | shares	(69,240)
Balance, end of year, Number of SARs (shares) | shares	1,160,828
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Balance, beginning of year, Weighted Average Exercise Price of SARs (dollars per share)	$ 140.53
Granted, Weighted Average Exercise Price of SARs (dollars per share)	140.28
Exercised, Weighted Average Exercise Price of SARS (dollars per share)	136.16
Forfeited, Weighted Average Exercise Price of SARs (dollars per share)	142.19
Balance, end of year, Weighted Average Exercise Price of SARs (dollars per share)	$ 140.51
Balance, end of year, Weighted Average Remaining Contractual Term (in years)	1 year 5 months 5 days
Balance, end of year, Aggregate Intrinsic Value | $	$ 11,063
Closing price per share, ordinary shares (dollars per share)	$ 150.04