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Expiration period by share based payment award in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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The estimated amount of dividends per share to be paid to holders of the underlying shares (expected dividends) over the option's term.

+ References

No definition available.

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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 dividends declared during the period for each share of common stock outstanding.

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The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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The number of shares issued pursuant to the terms of the deferred compensation plan as of the balance sheet date.

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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 cash outflow paid by the company to cover an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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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).

+ 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).

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

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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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.

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Gross 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.

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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.

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Period Type:	instant

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- Definition

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

+ References

+ Details

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- Definition

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.

+ References

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

+ References

No definition available.

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- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28,29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-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

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Share Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	May 31, 2013	May 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 10, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares provided under plan (in shares)							9,100,000
Stock-based compensation expense recorded			$ 12,368	$ 10,780	$ 8,646
Dividends declared per share (in dollars per share)	$ 5.00	$ 6.00	$ 5.00	$ 6.00	$ 0
Payments for employees' tax obligations to taxing authorities			15,020	6,425	371
Weighted-average assumptions [Abstract]
Weighted average grant date fair value (in dollars per share)			$ 16.30	$ 12.13	$ 11.10
Assumptions [Abstract]
Expected stock price volatility (in hundredths)			47.00%	45.00%	50.00%
Risk free interest rate (in hundredths)			1.21%	1.22%	2.69%
Expected annual dividend per share (in dollars per share)			$ 0	$ 0	$ 0
Expected life of options			6 years 3 months	6 years 3 months	6 years 6 months
Number of Options [Roll Forward]
Outstanding, Beginning balance (in shares)			3,440,042	4,308,545	4,236,259
Granted (in shares)			253,857	256,112	179,877
Exercised (in shares)			(703,326)	(1,113,827)	(107,591)
Expired (in shares)			(1,625)	0	0
Forfeited (in shares)			(51,647)	(10,788)	0
Outstanding, Ending balance (in shares)			2,937,301	3,440,042	4,308,545	4,236,259
Exercisable (in shares)			802,034
Weighted-Average Exercise Price [Roll Forward]
Outstanding, Beginning balance (in dollars per share)			$ 14.38	$ 13.36	$ 13.02
Granted (in dollars per share)			$ 35.04	$ 21.28	$ 21.26
Exercised (in dollars per share)			$ 6.05	$ 13.21	$ 13.00
Expired (in dollars per share)			$ 20.94	$ 0	$ 0
Forfeited (in dollars per share)			$ 17.02	$ 20.52	$ 0
Outstanding, Ending balance (in dollars per share)			$ 5.74	$ 14.38	$ 13.36	$ 13.02
Exercisable (in dollars per share)			$ 2.82
Weighted Average Remaining Contractual Term (in years) [Abstract]
Outstanding			9 years 6 months	9 years	8 years 2 months 12 days	9 years 1 month 6 days
Exercisable			9 years 6 months
Aggregate Intrinsic Value [Abstract]
Outstanding			148,369	68,549	63,193	13,349
Exercisable			42,856
Board of Directors [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Stock granted to certain members of board of directors (in shares)			7,291	10,864	16,680
Compensation cost for stock granted to certain members of board of directors			260	300	300
Minimum [Member]
Weighted-Average Exercise Price [Roll Forward]
Granted (in dollars per share)			$ 29.81	$ 15.94	$ 6.15
Maximum [Member]
Weighted-Average Exercise Price [Roll Forward]
Granted (in dollars per share)			$ 48.36	$ 32.05	$ 13.73
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recorded			9,034	6,835	6,475
Dividends declared per share (in dollars per share)			$ 5.00	$ 6.00
Vesting period			4 years	4 years	5 years	5 years
Expiration period			10 years	10 years	10 years	10 years
Shares withheld for tax withholding (in shares)			323,427	667,401	55,202
Payments for employees' tax obligations to taxing authorities			8,449	6,425	371
Aggregate Intrinsic Value [Abstract]
Unrecognized compensation cost			11,855
Non-vested Stock Awards, Weighted Average Grant Date Fair Value [Roll Forward]
Unrecognized compensation cost, weighted-average period			2 years
Restricted Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recorded			3,074	3,645	1,871
Vesting period			3 years
Shares withheld for tax withholding (in shares)			163,458	0	0
Payments for employees' tax obligations to taxing authorities			6,571	0	0
Aggregate Intrinsic Value [Abstract]
Unrecognized compensation cost			$ 5,216
Non-vested Stock Awards, Shares [Roll Forward]
Outstanding, Beginning balance (in shares)			665,071	489,302	430,155
Granted (in shares)			112,494	195,771	59,147
Vested (in shares)			(450,537)	0	0
Forfeited (in shares)			(22,622)	(20,002)	0
Outstanding, Ending balance (in shares)			304,406	665,071	489,302
Non-vested Stock Awards, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding, Beginning balance (in dollars per share)			$ 17.75	$ 13.93	$ 13.02
Granted (in dollars per share)			$ 37.82	$ 26.94	$ 20.59
Vested (in dollars per share)			$ 14.21	$ 0	$ 0
Forfeited (in dollars per share)			$ 25.36	$ 11.96	$ 0
Outstanding, Ending balance (in dollars per share)			$ 29.68	$ 17.75	$ 13.93
Unrecognized compensation cost, weighted-average period			1 year 10 months 24 days