Stock Compensation Plans - SSAR's and Stock Option Activity (Detail) - SSAR's and Stock Options [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance at December 31, 2013, Shares Subject to SSAR's/Options	38
Exercised, Shares Subject to SSAR's/Options	(17)
Cancelled, Shares Subject to SSAR's/Options	(2)
Balance at December 31, 2014, Shares Subject to SSAR's/Options	19	38
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Balance at December 31, 2013, Weighted Average Exercise Price	$ 52.10
Exercised, Weighted Average Exercise Price	46.72
Cancelled, Weighted Average Exercise Price	41.16
Balance at December 31, 2014, Weighted Average Exercise Price	$ 59.14	$ 52.10
SSARs/ Options Exercisable	18	38