Consolidated Statement of Shareholders' Equity (unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Stockholders' Equity [Abstract]
Dividends, per share (in dollars per share)	$ 0.1425	$ 0.13	$ 0.4275	$ 0.39