Earnings Per Share - Weighted Average Number of Shares Outstanding (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted average number of shares outstanding:
Basic Common	83,420	84,007	78,875
Dilutive impact of Equity Incentive Plans:
Common shares	1,974	1,500	1,443
Diluted common shares	85,394	85,507	80,318