Restructuring Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		$ 10.2
Restructuring costs incurred to date	0.2	5.3
Increase (Decrease) in Restructuring Liability [Roll Forward]
Balance at December 31, 2011		0
Costs paid or otherwise settled		(5.1)
Balance at September 30, 2012	0.2	0.2
Number of regional offices created		1
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		3.7
Restructuring costs incurred to date	0.2	2.1
Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		5.9
Restructuring costs incurred to date	0	3.2
Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.6
Restructuring costs incurred to date	0	0
QEP Energy [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		9.5
Restructuring costs incurred to date	0.2	5.3
Increase (Decrease) in Restructuring Liability [Roll Forward]
Balance at December 31, 2011		0
Costs paid or otherwise settled		(5.1)
Balance at September 30, 2012	0.2	0.2
QEP Energy [Member] | One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		3.4
Restructuring costs incurred to date	0.2	2.1
QEP Energy [Member] | Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		5.5
Restructuring costs incurred to date	0	3.2
QEP Energy [Member] | Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.6
Restructuring costs incurred to date	0	0
QEP Field Services [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.2
Restructuring costs incurred to date	0	0
Increase (Decrease) in Restructuring Liability [Roll Forward]
Balance at December 31, 2011		0
Costs paid or otherwise settled		0
Balance at September 30, 2012	0	0
QEP Field Services [Member] | One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0
Restructuring costs incurred to date	0	0
QEP Field Services [Member] | Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.2
Restructuring costs incurred to date	0	0
QEP Field Services [Member] | Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0
Restructuring costs incurred to date	0	0
QEP Marketing [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.5
Restructuring costs incurred to date	0	0
Increase (Decrease) in Restructuring Liability [Roll Forward]
Balance at December 31, 2011		0
Costs paid or otherwise settled		0
Balance at September 30, 2012	0	0
QEP Marketing [Member] | One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.3
Restructuring costs incurred to date	0	0
QEP Marketing [Member] | Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0.2
Restructuring costs incurred to date	0	0
QEP Marketing [Member] | Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs		0
Restructuring costs incurred to date	$ 0	$ 0