Amount of shares earned as a % of target award.

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Share-based Compensation Arrangement by Share-based Payment Award, Award percentage attained

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Award percentage earned based on metric over the performance period.

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Number of performance metrics in restricted shares award type plan.

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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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Number of shares issued pursuant to the terms of a deferred compensation arrangement.

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-Name Accounting Standards Codification
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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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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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No definition available.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, 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 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 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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Equity Awards - Restricted Shares Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) number Rate	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) number shares	Jun. 30, 2016 USD ($)	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares issued related to director fee deferrals			7,124
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Unvested Restricted Shares Granted			351,094
Unrecognized unvested restricted shares-based compensation expense \| $	$ 9.3		$ 9.3
Weighted-average period for recognition of the unrecognized unvested restricted shares-based compensation expense			2 years 3 months
Restricted shares-based compensation expense \| $	$ 1.7	$ 2.2	$ 3.0	$ 4.1
Plan 1 [Member] \| Service-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Unvested Restricted Shares Granted			189,062
Award requisite service period			3 years
Plan 5 [Member] \| Service-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award requisite service period			1 year
Plan 5 [Member] \| Service-based restriced shares [Member] \| Non-employee independent director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Unvested Restricted Shares Granted			30,429
Plan 8 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance metrics in restricted shares award type plan \| number	2		2
Plan 8 [Member] \| Performance-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Unvested Restricted Shares Granted			111,761
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.52%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate \| Rate	35.60%
3 year EPS CAGR metric [Member] \| Minimum [Member] \| Plan 8 [Member] \| Performance-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Amount of shares earned % of target award	40.00%
3 year EPS CAGR metric [Member] \| Maximum [Member] \| Plan 8 [Member] \| Performance-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award percentage earned based on metric over the performance period	50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Amount of shares earned % of target award	200.00%
Total shareholder return metric [Member] \| Minimum [Member] \| Plan 8 [Member] \| Performance-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Amount of shares earned % of target award	0.00%
Total shareholder return metric [Member] \| Maximum [Member] \| Plan 8 [Member] \| Performance-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award percentage earned based on metric over the performance period	50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Amount of shares earned % of target award	200.00%
EPS CAGR and cash generation metric [Member] \| Plan 3 [Member] \| Performance-based restriced shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Unvested Restricted Shares Granted			12,718
Share-based Compensation Arrangement by Share-based Payment Award, Award percentage attained					121.10%