Stockholders' Equity - Summary of the Companys Change in the Common Stock (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Outstanding shares of voting common stock at the beginning of year	37,409,274
Exercise of stock options	195,410	196,034	165,340
Outstanding shares of voting common stock at the end of year	37,543,775	37,409,274
Voting Common Stock [Member]
Class of Stock [Line Items]
Outstanding shares of voting common stock at the beginning of year	37,409,000	37,319,000	37,729,000
Exercise of stock options	181,000	183,000	120,000
Issuance of restricted stock, net of shares withheld for tax payments and cancellations	104,000	178,000	116,000
Repurchases	(150,000)	(271,000)	(646,000)
Outstanding shares of voting common stock at the end of year	37,544,000	37,409,000	37,319,000