Shareholders' Equity - Dividends (Details) - $ / shares	2 Months Ended	3 Months Ended																12 Months Ended
	Feb. 22, 2017	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2015	[1]	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2016	[1]	Dec. 31, 2015	[1]	Dec. 31, 2014
Class of Stock [Line Items]
Dividends (in dollars per share)		$ 0.13		$ 0.13		$ 0.13		$ 0.13		$ 0.12		$ 0.12		$ 0.12		$ 0.12		$ 0.52		$ 0.48		$ 0.44
Subsequent Event [Member]
Class of Stock [Line Items]
Dividends (in dollars per share)	$ 0.1425
Increase in common stock dividend (as a percent)	10.00%

[1] Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.