QEP Midstream (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Aug. 14, 2013	Mar. 31, 2014
Noncontrolling Interest [Line Items]
Initial Offering Period	August 14, 2013
Shares Issued, Price Per Share	$ 21.00
Total proceeds from the Subsidiary IPO	$ 483.0
Offering costs	33.4
Net proceeds from Subsidiary IPO	449.6
Noncontrolling Interest, Ownership Percentage by Parent		57.80%
Limited Partner Common Units Sold to Public [Member]
Noncontrolling Interest [Line Items]
Partners' Capital Account, Units, Sold in Public Offering	20,000,000
Offering costs	29.3
Net proceeds from Subsidiary IPO	390.7
Limited Partner Common Units Sold to Underwriters [Member]
Noncontrolling Interest [Line Items]
Partners' Capital Account, Units, Sold in Public Offering	3,000,000
Offering costs	4.1
Net proceeds from Subsidiary IPO	$ 58.9