Equity-Based Compensation Plans (Summary Of Service-Based And Performance-Based Awards) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Service-Based Awards [Member]
Number of Phantom Units
Unvested at December 31, 2015 (in shares) | shares	132,676
Granted (in shares) | shares	84,997
Forfeited (in shares) | shares	(3,117)
Settled (in shares) | shares	(33,326)
Unvested at December 31, 2016 (in shares) | shares	181,230.00
Average Grant Date Fair Value
Unvested at December 31, 2015 (in dollars per share) | $ / shares	$ 48.09
Granted (in dollars per share) | $ / shares	31.67
Forfeited (in dollars per share) | $ / shares	45.88
Settled (in dollars per share) | $ / shares	47.19
Unvested at December 31, 2016 (in dollars per share) | $ / shares	$ 40.59
Total Value (in thousands)
Unvested at December 31, 2015 | $	$ 6,380
Granted | $	2,692
Forfeited | $	(143)
Settled | $	(1,573)
Unvested at December 31, 2016 | $	$ 7,356
Performance-Based Awards [Member]
Number of Phantom Units
Unvested at December 31, 2015 (in shares) | shares	344,208
Granted (in shares) | shares	254,587
Forfeited (in shares) | shares	(4,677)
Settled (in shares) | shares	(110,886)
Unvested at December 31, 2016 (in shares) | shares	483,232.000
Average Grant Date Fair Value
Unvested at December 31, 2015 (in dollars per share) | $ / shares	$ 47.78
Granted (in dollars per share) | $ / shares	30.38
Forfeited (in dollars per share) | $ / shares	45.89
Settled (in dollars per share) | $ / shares	46.97
Unvested at December 31, 2016 (in dollars per share) | $ / shares	$ 38.82
Total Value (in thousands)
Unvested at December 31, 2015 | $	$ 16,446
Granted | $	7,734
Forfeited | $	(215)
Settled | $	(5,208)
Unvested at December 31, 2016 | $	$ 18,757