Accumulated service period for voluntary termination.

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Age limit of voluntary termination of employment.

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Amount of participant contribution.

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Number of shares to be issued under deferred compensation plan included in shares outstanding.

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Percentage of plan contribution.

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Share-based Compensation Arrangement by Share-based Payment Award, Cliff Vesting, Minimum

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Share based compensation arrangement by share based payment award terms of purchase common shares under ESPP.

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Voluntary termination of employment terms.

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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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Amount of discretionary contributions made by an employer to a defined contribution plan.

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

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Unrecognized cost of unvested share-based compensation awards.

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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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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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Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

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Discount rate from fair value on purchase date that participants pay for shares.

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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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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 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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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Number of non-vested options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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

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Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.

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Share Based and Deferred Compensation (Details Textuals) (USD $)	12 Months Ended			3 Months Ended	0 Months Ended			12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Mar. 11, 2014	Mar. 12, 2014	Mar. 01, 2012	Feb. 25, 2014	Feb. 25, 2013
Share Based and Deferred Compensation (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	2,684,795	2,983,569		2,684,795
Stock-based compensation expense, capitalized	$ 1,700,000	$ 1,400,000	$ 2,600,000
Stock-based compensation expense	6,100,000	8,300,000	8,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	184,116
Defined Contribution Plan, Employer Discretionary Contribution Amount	400,000	400,000	400,000
Stock Option [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	2,684,795			2,684,795
Stock-based compensation expense, capitalized	0	100,000	500,000
Stock-based compensation expense	0	700,000	1,600,000
Deferred Compensation Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Deferred compensation arrangement with individual increase in compensation expense.	0	200,000	300,000
Number of shares to be issued under deferred compensation plan included in total shares outstanding	400,000	300,000		400,000
Restricted Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	229,119
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	18,597
Share Based and Deferred Compensation (Textuals) [Abstract]
Unrecognized compensation expenses	2,400,000			2,400,000
Weighted average period over which options will be recognized	1 year 5 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	540,066	563,713		540,066
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	three years from the initial grant dates
Stock-based compensation expense	2,700,000	3,200,000	3,400,000
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		600,000	900,000	600,000
Share-based Compensation Arrangement by Share-based Payment Award, Cliff Vesting, Minimum	3 years
Voluntary termination of employment terms	after reaching age 57 and accumulating at least 15 years of service with the Company
Accumulated Service Period For Voluntary Termination	15 years
Restricted Performance Share Units Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Unrecognized compensation expenses	2,100,000			2,100,000
Weighted average period over which options will be recognized	1 year 0 months 0 days
Stock-based compensation expense		4,400,000	3,500,000	3,200,000
Vesting Period, Minimum	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost		800,000	1,200,000	1,100,000
Voluntary termination of employment terms	after reaching age 57 and accumulating at least 15 years of service with the Company
Accumulated Service Period For Voluntary Termination	15 years
Employee Share Purchase Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Stock-based compensation expense	100,000	100,000	100,000
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	15.00%
Aggregate share-based awards awarded to executives	1,250,000			1,250,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	400,000	400,000	400,000
Share purchases made by employees under ESPP	85% of the average closing price per share for a specified period
Percentage of plan contribution	20.00%
Amount of participant contribution	50,000			50,000
Executive Officer [Member] \| Restricted Share Awards [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	65,955			65,955		129,245
Age limit of voluntary termination of employment	57
Executive Officer [Member] \| Restricted Performance Share Units Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	196,004
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	69,822
Share Based and Deferred Compensation (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	599,397	473,215		599,397
Aggregate share-based awards awarded to executives					134,284	61,720	265,222.00		231,093
Fair value of awards on the grant date					$ 2,624,000	$ 1,225,000	$ 4,273,000	$ 4,137,000
Cliff Vesting [Member] \| Executive Officer [Member] \| Restricted Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period						131,641
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	2,396