Equity-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Stock Options [Line Items]
Shares available for future grants	12,000,000
Equity-based compensation	$ 27.1	$ 25.6	$ 22.0
Total compensation expense related to share-based compensation	27.1	25.6	22.0
Stock Options [Member]
Share-based Compensation, Stock Options [Line Items]
Fair value of options at grant date	$ 15.16	$ 14.29	$ 18.80
Risk-free interest rate range, minimum	0.97%
Risk-free interest rate range, maximum	1.84%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum	51.50%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate	58.30%	55.90%	54.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	58.50%
Weighted-average risk-free interest rate	1.00%	0.80%	2.10%
Expected dividend yield (in hundredths)	0.27%	0.26%	0.21%
Expected life in years	5 years 6 months	5 years	5 years
Weighted-Average Price [Abstract]
Weighted-Average Price, beginning (in dollars per share)	$ 25.23
Weighted-Average Price, Granted (in dollars per share)	$ 30.06
Weighted-Average Price, Exercised (in dollars per share)	$ 10.77
Options Outstanding [RollForward]
Outstanding at December 31, 2012 (in shares)	1,697,471
Granted (in shares)	330,592
Exercised (in shares)	(224,833)
Forfeited (in shares)	9,043
Outstanding at December 31, 2013 (in shares)	1,794,187	1,697,471
Options Excercisable (in shares)	1,288,844
Unvested Options (in shares)	505,343
Weighted-Average Price, Forfeited (in dollars per share)	$ 30
Weighted-Average Price, Ending (in dollars per share)	$ 27.90	$ 25.23
Weighted-Average Price, Options Excercisable	$ 26.63
Weighted-Average Price, Unvested Options	$ 31.14
Weighted-Average Remaining Contractual Term, Outstanding	3 years 8 months 1 day
Aggregate Intrinsic Value, Outstanding	6.5
Weighted-Average Remaining Contractual Term, Options Excercisable	2 years 10 months 24 days
Aggregate Intrinsic Value, Options Excercisable	6.4
Weighted-Average Remaining Contractual Term, Unvested Options	5 years 10 months 16 days
Aggregate Intrinsic Value, Unvested Options	0.1
Intrinsic value of options exercised	4.3	9.6	2.7
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	1.4	4.6	0.4
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	6.5
Unrecognized compensation cost	2.9
Weighted-average period for recognition of compensation costs	1 year 11 months 12 days
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options	2.0
Restricted Stock [Member]
Options Outstanding [RollForward]
Weighted-Average Price, beginning balance (in dollars per share)	$ 31.78
Weighted-Average Price, Granted (in dollars per share)	$ 30.06	$ 30.54	$ 38.50
Weighted-Average Price, Vested (in dollars per share)	$ 31.42
Weighted-Average Price, Forfeited (in dollars per share)	$ 30.77
Weighted-Average Price, Ending Balance (in dollars per share)	$ 30.96	$ 31.78
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	0.8
Unrecognized compensation cost	17.4
Weighted-average period for recognition of compensation costs	1 year 11 months 28 days
Total fair value of stock that vested	19.8	16.7	11.7
Employee Service Share-Based Compensation Tax Expense	(0.1)	(0.3)	1.0
Restricted Shares Outstanding [Roll Forward]
Balance, beginning (in shares)	1,300,588
Granted (in shares)	862,669
Vested (in shares)	(665,963)
Forfeited (in shares)	(108,341)
Balance, Ending (in shares)	1,388,953	1,300,588
Restricted Stock [Member] \| Minimum [Member]
Options Outstanding [RollForward]
Vesting period (in years)	3 years
Performance Share Units [Member]
Options Outstanding [RollForward]
Weighted-Average Price, beginning balance (in dollars per share)	$ 33.91
Weighted-Average Price, Granted (in dollars per share)	$ 30.12	$ 30.75	$ 39.07
Weighted-Average Price, Vested (in dollars per share)	$ 0.00
Weighted-Average Price, Forfeited (in dollars per share)	$ (30.69)
Weighted-Average Price, Ending Balance (in dollars per share)	$ 32.33	$ 33.91
Unrecognized compensation cost	6.4
Weighted-average period for recognition of compensation costs	1 year 9 months 28 days
Restricted Shares Outstanding [Roll Forward]
Balance, beginning (in shares)	283,484
Granted (in shares)	223,844
Vested (in shares)	0
Forfeited (in shares)	(26,668)
Balance, Ending (in shares)	480,660	283,484
QEP Midstream Long-Term Incentive Plan [Member]
Share-based Compensation, Stock Options [Line Items]
Equity-based compensation	$ 0.5

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The weighted-average price as of the balance sheet date for unvested stock options.

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The estimated minimum dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of unvested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.

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The number of shares into which unvested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted average period between the balance sheet date and expiration for all unvested portions of options outstanding under the plan, which may be expressed in a decimal value for number of years.

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Adjustment to additional paid in capital related to the net effect of excess tax benefits and tax deficiencies associated with an equity-based compensation plan other than an employee stock ownership plan (ESOP).

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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No definition available.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The range of expected volatilities used and the weighted-average expected volatility for an entity using a valuation technique with different volatilities during the contractual term.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Number of share options (or share units) exercised during the current period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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