Stockholders' Equity - Summary of the Companys Change in the Common Stock (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Outstanding shares of voting common stock at the beginning of year	37,639,917
Exercise of stock options	106,899	120,588	380,967
Outstanding shares of voting common stock at the end of year	37,935,984	37,639,917
Voting Common Stock [Member]
Class of Stock [Line Items]
Outstanding shares of voting common stock at the beginning of year	37,640,000	37,621,000	37,544,000
Exercise of stock options	107,000	121,000	262,000
Issuance of restricted stock, net of shares withheld for withholding tax payments and cancellations	103,000	22,000	39,000
Treasury shares used for acquisition	146,000
Repurchases	(60,000)	(124,000)	(224,000)
Outstanding shares of voting common stock at the end of year	37,936,000	37,640,000	37,621,000