Financing Activities - Distributions (Details) - $ / shares	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Distributions (Numeric) [Abstract]
Quarterly common stock dividend declaration date	2016-05
Dividend payable date of quarterly common stock dividend	Jul. 01, 2016
Current quarterly common stock dividend (in dollars per share)	$ 0.38	$ 0.38	$ 0.3725	$ 0.76	$ 0.7450
Annualized current quarterly common stock dividend (in dollars per share)	$ 1.52