Stockholders' Equity and Earnings Per Common Share - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stockholders Equity and Earnings Per Common Share Additional Information [Abstract]
Commission Paid on Common Stock Repurchased	$ 0.2	$ 0.0
Exercise Price Floor on Outstanding Stock Options	$ 23.35
Exercise Price Ceiling on Outstanding Stock Options	26.29
Outstanding Restricted Stock Unit Grant Prices Lower Limit	27.85
Outstanding Restricted Stock Unit Grant Prices Upper Limit	55.26
Outstanding Performance Share Unit Awards Grant Price Range Lower Limit	27.85
Outstanding Performance Share Unit Awards Grant Price Range Upper Limit	$ 49.86
Number of Antidilutive Securities Excluded from Computation of Earnings Per Share		400,000
Authorized Shares of Preferred Stock	25,000,000
Par Value Per Share of Preferred Stock	$ 0.10
Issued Shares of Preferred Stock	0