Subsequent Events - Equity (Details) - $ / shares	1 Months Ended																			3 Months Ended		9 Months Ended
	Oct. 31, 2017	Sep. 30, 2017	Aug. 31, 2017	Jul. 31, 2017	Jun. 30, 2017	May 31, 2017	Apr. 30, 2017	Mar. 31, 2017	Feb. 28, 2017	Jan. 31, 2017	Sep. 30, 2016	Aug. 31, 2016	Jul. 31, 2016	Jun. 30, 2016	May 31, 2016	Apr. 30, 2016	Mar. 31, 2016	Feb. 29, 2016	Jan. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity
Dividends per share declared (in dollars per share)		$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.57	$ 0.54	$ 1.71	$ 1.62
Dividend Payable, October 31, 2017 | Subsequent Event | Common Stock
Equity
Dividends per share declared (in dollars per share)	$ 0.19
Dividend Payable, November 30, 2017 | Subsequent Event | Common Stock
Equity
Dividends per share declared (in dollars per share)	0.19
Dividend Payable, December 29, 2017 | Subsequent Event | Common Stock
Equity
Dividends per share declared (in dollars per share)	$ 0.19