Incentive Plan (Summary Of Long-Term Incentive Units) (Details) - Long-Term Incentive Units	9 Months Ended
	Sep. 30, 2015 $ / shares shares
Long-Term Incentive Unit Activity [Roll Forward]
Unvested Shares, beginning of period, Shares	314,415
Unvested Shares, Granted, Shares	90,679
Unvested Shares, Vested, Shares	(157,300)
Unvested Shares, Cancelled or expired, Shares	(22,496)
Unvested Shares, end of period, Shares	225,298
Unvested Shares, beginning of period, Weighted-Average Grant Date Fair Value ($ per share) | $ / shares	$ 59.34
Unvested Shares, Granted, Weighted-Average Grant Date Fair Value ($ per share) | $ / shares	64.79
Unvested Shares, Vested, Weighted-Average Grant Date Fair Value ($ per share) | $ / shares	60.25
Unvested Shares, Cancelled or expired, Weighted-Average Grant Date Fair Value ($ per share) | $ / shares	58.13
Unvested Shares, beginning of period, Weighted-Average Grant Date Fair Value ($ per share) | $ / shares	$ 61.03