Changes in Issued and Outstanding Common Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity [Abstract]
Beginning balance	14,281,000	14,198,000	14,047,000
Vested stock grants	127,000	59,000	50,000
Employee stock purchase plan	21,000	19,386	17,000
Stock options exercised	1,500	5,250	83,500
Ending balance	14,431,000	14,281,000	14,198,000