Income Taxes Income Taxes (Schedule of Dividends Paid, Per Share) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common Stock, Dividends, Per Share, Cash Paid	$ 3.40	$ 3.08	$ 3.12
Ordinary Income [Member]
Common Stock, Dividends, Per Share, Cash Paid	2.62808	2.535481	2.85895
Capital Gain [Member]
Common Stock, Dividends, Per Share, Cash Paid	0.69110	0	0.16493
Return of Capital [Member]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.08082	$ 0.544519	$ 0.09612