Summary of Significant Accounting Policies (Deferred Financing and Leasing Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Capitalized compensation, leasing costs	$ 3.8	$ 4.6	$ 3.9