Restructuring Costs - Summary of Restructuring Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			$ 7.9
Restructuring Charges	0	0.3	0	0.8
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			3.6
Restructuring Charges	0	0.2	0	0.5
Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			3.7
Restructuring Charges	0	0.1	0	0.3
Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			0.6
Restructuring Charges	0	0	0	0
QEP Energy [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			7.6
Restructuring Charges	0	0.2	0	0.7
QEP Energy [Member] | One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			3.3
Restructuring Charges	0	0.1	0	0.4
QEP Energy [Member] | Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			3.7
Restructuring Charges	0	0.1	0	0.3
QEP Energy [Member] | Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			0.6
Restructuring Charges	0	0	0	0
QEP Marketing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			0.3
Restructuring Charges	0	0.1	0	0.1
QEP Marketing [Member] | One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred from inception to reporting date			0.3
Restructuring Charges	$ 0	$ 0.1	$ 0	$ 0.1