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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The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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

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Share Based Compensation Restricted Performance Share Units (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 01, 2015	Feb. 06, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
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, Award Vesting Period	3 years
Allocated Share-based Compensation Expense	2.4	$ 1.7
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	0.5	0.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	3.8
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 8 months 12 days
Dividends Payable, Amount Per Share				$ 0.15
March 1, 2012 RSPU Grant [Member] \| Restricted Performance Share Units Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested, shares			468,056