Incentive Plan (Summary of Stock Options Outstanding and Exercisable) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Exercise price range, lower (in dollars per share)	$ 41.73
Exercise price range, upper (in dollars per share)	$ 41.73
Number outstanding (shares)	6	17,674
Weighted-average remaining contractual life (years)	32 days
Weighted average exercise price, outstanding (in dollars per share)	$ 41.73
Aggregate intrinsic value	$ 388