Earnings Per Share - Weighted Average Number of Shares Outstanding (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted average number of shares outstanding:
Basic Common	82,969	83,420	84,007
Dilutive impact of Equity Incentive Plans:
Common shares	1,630	1,974	1,500
Diluted common shares	84,599	85,394	85,507