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

No definition available.

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- Definition

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.

+ References

No definition available.

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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.

+ References

No definition available.

+ Details

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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.

+ References

No definition available.

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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.

+ References

No definition available.

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- Definition

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).

+ References

No definition available.

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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.

+ References

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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.

+ References

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-Paragraph 28

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-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

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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.

+ References

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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.

+ References

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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).

+ References

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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).

+ References

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-Publisher FASB

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-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

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-Paragraph A240

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-Paragraph A240

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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.

+ References

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-Publisher FASB

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-SubTopic 10

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-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

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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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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-Subparagraph (c)(2)(i)-(ii)

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-Paragraph A240

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- Definition

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

+ References

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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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.D.2)

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-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(i)

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section D

-Subsection 2

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The estimated measure of the minimum 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.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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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.

+ References

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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.

+ References

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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.

+ References

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

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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)

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-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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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.

+ References

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.

+ References

No definition available.

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

+ References

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

+ References

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

+ References

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-Name Regulation S-X (SX)

-Number 210

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-Article 3

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-Paragraph 2

-Subparagraph (c)(1)(iv)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Share-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation [Abstract]
Shares available for future grants	11,900,000		11,900,000
Weighted-Average Price [Abstract]
Share-based compensation	$ 6.8	$ 7.2	$ 20.0	$ 19.5
Stock Options [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Fair value of options at grant date			$ 15.16
Risk-free interest rate (in hundredths)			1.00%
Expected price volatility (in hundredths)			58.30%
Expected dividend yield (in hundredths)			0.27%
Expected life in years			5 years 6 months
Options Outstanding [RollForward]
Outstanding Beginning Balance (in shares)			1,697,471
Granted (in shares)			330,592
Exercised (in shares)			(209,500)
Forfeited (in shares)			0
Outstanding Ending Balance (in shares)	1,818,563		1,818,563
Options Excercisable (in shares)	1,236,211		1,236,211
Unvested Options (in shares)	582,352		582,352
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			1.4	2.2
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net			1.4
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)			$ 9.60
Weighted-Average Price, Forfeited (in dollars per share)			$ 0
Weighted-Average Price, Ending (in dollars per share)	$ 27.90		$ 27.90
Weighted-Average Price, Options Excercisable	$ 26.36		$ 26.36
Weighted-Average Price, Unvested Options	$ 31.18		$ 31.18
Weighted-Average Remaining Contractual Term, Outstanding			3 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding	3.6		3.6
Weighted-Average Remaining Contractual Term, Options Excercisable			3 years 0 months 0 days
Aggregate Intrinsic Value, Options Excercisable	3.6		3.6
Weighted-Average Remaining Contractual Term, Unvested Options			5 years 10 months 24 days
Aggregate Intrinsic Value, Unvested Options	0		0
Intrinsic value of options exercised			4.2	7.1
Unrecognized compensation cost	4.4		4.4
Weighted-average period for recognition of compensation costs			2 years 1 month 24 days
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options			0.5
Restricted Stock [Member]
Options Outstanding [RollForward]
Total fair value of stock that vested			18.4	16.6
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			(0.4)	(0.2)
Restricted Shares Outstanding [Roll Forward]
Balance, beginning (in shares)			1,300,588
Granted (in shares)			850,824
Vested (in shares)			(620,065)
Forfeited (in shares)			(75,442)
Balance, Ending (in shares)	1,455,905		1,455,905
Weighted-Average Price [Abstract]
Weighted-Average Price, beginning balance (in dollars per share)			$ 31.78
Weighted-Average Price, Granted (in dollars per share)			$ 30.03	$ 30.59
Weighted-Average Price, Vested (in dollars per share)			$ 31.42
Weighted-Average Price, Forfeited (in dollars per share)			$ 30.82
Weighted-Average Price, Ending Balance (in dollars per share)	$ 30.96		$ 30.96
Unrecognized compensation cost	23.5		23.5
Weighted-average period for recognition of compensation costs			2 years 2 months 4 days
Restricted Stock [Member] \| Minimum [Member]
Weighted-Average Price [Abstract]
Vesting period (in years)			3 years 0 months 0 days
Performance Share Units [Member]
Restricted Shares Outstanding [Roll Forward]
Balance, beginning (in shares)			283,484
Granted (in shares)			223,844
Vested (in shares)			0
Forfeited (in shares)			(1,163)
Balance, Ending (in shares)	506,165		506,165
Weighted-Average Price [Abstract]
Weighted-Average Price, beginning balance (in dollars per share)			$ 34.01
Weighted-Average Price, Granted (in dollars per share)			$ 30.12	$ 30.90
Weighted-Average Price, Vested (in dollars per share)			$ 0.00
Weighted-Average Price, Forfeited (in dollars per share)			$ (30.12)
Weighted-Average Price, Ending Balance (in dollars per share)	$ 32.30		$ 32.30
Unrecognized compensation cost	8.5		8.5
Weighted-average period for recognition of compensation costs			2 years 0 months 0 days
QEP Midstream Long-Term Incentive Plan [Member]
Weighted-Average Price [Abstract]
Share-based compensation			$ 0.1