Tax Treatment of Distributions (Details) - $ / shares			3 Months Ended	12 Months Ended
	Jan. 13, 2017	Dec. 13, 2016	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Dividends declared per common share		$ 1.90	$ 0.375	$ 3.375	$ 1.4	$ 1.40
Dividends paid per common share				1.587
Common stock [Member]
Class of Stock [Line Items]
Dividends declared per common share			$ 2.275	3.375	1.400	1.400
Less: Dividends declared in the current year and paid in the following year				(2.275)	(0.350)	(0.350)
Add: Dividends declared in the prior year and paid in the current year				0.350	0.350	0.350
Dividends paid per common share				$ 1.450	$ 1.400	$ 1.400
Scenario, forecast [Member]
Class of Stock [Line Items]
Dividends paid per common share	$ 0.313