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The number of units exercisable at period end.

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No definition available.

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The weighted average exercise price of warrants exercised during the period.

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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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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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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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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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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 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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average remaining contractual term for equity-based awards excluding options, 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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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 estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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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 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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Other than shares newly issued, the number of additional shares issued (for example, a stock split) or canceled (for example, to correct a share issuance), during the period under the plan.

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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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Share-Based Awards (Details - Other Details) $ in Millions	12 Months Ended
Share-Based Awards (Details - Other Details) $ in Millions	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2009 shares
Share Based Compensation Arrangements - Other details
Share based compensation expense \| $	$ 41.6	$ 34.4	$ 29.8
Tax benefit of share-based compensation expense \| $	7.4	6.9	3.3
Tax Benefit Realized from Exercise of Stock Options \| $	$ 10.2	$ 6.2	$ 7.0
Employee Equity Plan [Member]
Employee Equity Plan [Abstract]
Shares remaining for issuance	0
Share Options and SSARs [Member]
Employee Equity Plan [Abstract]
Vesting period for EEP shares	3 years
Contractual term, in years	10 years
RSUs and PSUs [Member]
Employee Equity Plan [Abstract]
Vesting period for EEP shares	3 years
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Roll Forward
Outstanding at January 1, 2015	932,622
Granted	264,018	333,358	329,174
Performance based adjustment	10,142
Vested	(313,078)
Forfeited	(32,096)
Outstanding at December 31, 2015	861,608	932,622
Share Based Compensation Arrangements - Other details
Weighted average grant date fair value \| $ / shares	$ 119.06	$ 98.86	$ 89.44
Fair value of units vested \| $	$ 22.4	$ 20.6	$ 22.8
Unrecognized share-based compensation expense \| $	$ 27.6
Weighted average period of recognition	1 year 8 months 26 days
SSARs [Member]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Roll Forward
Outstanding at January 1, 2015	1,492,926
Granted	72,918	153,797	125,561
Exercised	(574,120)
Outstanding at December 31, 2015	991,724	1,492,926
Exercisable at December 31, 2015	820,380
Share Based Compensation Arrangements - Other details
Weighted average grant date fair value \| $ / shares	$ 17.03	$ 14.62	$ 11.25
Unrecognized share-based compensation expense \| $	$ 1.1
Weighted average period of recognition	1 year 8 months
Assumptions:
Expected life	6 years	6 years	6 years
Expected volatility	17.70%	18.10%	18.30%
Risk-free interest rate	1.90%	1.90%	1.00%
Dividend yield	2.20%	2.20%	2.30%
Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Roll Forward
Granted				27,655
Exercised	8,110
Outstanding at December 31, 2015	557
Share Based Compensation Arrangements - Other details
Weighted average remaining contractual term	1 year
Weighted average exercise price, exercises during period \| $ / shares	31.25
Weighted average exercise price \| $ / shares	30.86