Stockholders' Equity and Earnings Per Common Share - Additional Information (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stockholders Equity and Earnings Per Common Share Additional Information [Abstract]
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	700,000	400,000	400,000	400,000
Authorized Shares of Preferred Stock	25,000,000		25,000,000
Par Value Per Share of Preferred Stock	$ 0.10		$ 0.10
Issued Shares of Preferred Stock	0		0