Capital Structure - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Preferred stock, shares authorized	2,000,000	2,000,000
Class B Common Stock [Member]
Class of Stock [Line Items]
Common stock, rights to vote	84
Class A Common Stock [Member]
Class of Stock [Line Items]
Common stock, rights to vote	one