Commitments and Contingencies (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) Number_Of_Sites	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Commitments and Contingencies (Textual) [Abstract]
Estimated cost to retire facilities | $	$ 127.1
Asset Retirement Obligation Additional Estimated Costs Attributable To Third Party Owners Undiscounted | $	18.1
Operating leases, rent expense | $	$ 15.1	$ 15.4	$ 15.0
Minimum [Member]
Commitments and Contingencies (Textual) [Abstract]
Notice required to cancel purchase agreements, days	30 days
Maximum [Member]
Commitments and Contingencies (Textual) [Abstract]
Notice required to cancel purchase agreements, days	120 days
Capital Addition Purchase Commitments [Member]
Commitments and Contingencies (Textual) [Abstract]
Purchase Obligation, Due in Next Twelve Months | $	$ 104.4
Kansas sites [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked	6
Sites completing assessment	4
Number of Sites With Limited Soil and Groundwater Impact	2
Number of Sites Requiring Additional Investigation	2
Kansas sites [Member] | U.S. Liquids [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked	5
Kansas sites [Member] | U.S. Gas [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked	1