Earnings Per Share - Common Share Dividends Declared Per Share (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Common share dividends declared per share	$ 0.19	$ 0.1725	$ 0.57	$ 0.5175