Long-Term Incentive Plan (Cash Flow Effects Of LTIP Settlements) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Partners' Capital Account, Units, Unit-based Compensation	216,679	350,552	354,529
Settlement of tax withholdings on long-term incentive compensation	$ 13,875	$ 14,376	$ 17,784
Payments for Other Taxes	1,200	1,400	1,700
Total Cash Taxes Paid (in millions)	$ 15,100	$ 15,800	$ 19,500