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Aggregate awards of performance share awards issued to an employee under a share-based compensation arrangement for purposes of computing diluted earnings per share. If all necessary conditions have been satisfied by the end of the reporting period, the performance share awards shall be included as of the beginning of the period in which the conditions were satisfied (or as of the date of the grant date, if later). If all necessary conditions have not been satisfied by the end of the reporting period, the number of contingently issuable shares included in the diluted EPS computation shall be based on the number of shares, if any, that would be issuable if the end of reporting period were the end of the contingency period.

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Aggregate awards of restricted stock units issued to an employee, agent or director under a share-based compensation arrangement for purposes of computing diluted earnings per share. Such restricted stock unit awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their settlement may be contingent upon vesting. Those restricted stock unit awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of restricted stock unit awards shall be computed using the treasury stock method. If the equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding.

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Aggregate awards of share options issued to an employee, agent or director under a share-based compensation arrangement for purposes of computing diluted earnings per share. Such share options shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon vesting. Those share options are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share options shall be computed using the treasury stock method. If the equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding.

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Net income after adjustments for dividends on preferred stock (declared in the period), cumulative preferred stock (accumulated for the period), and redemption amounts of redeemable noncontrolling interests.

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Amount of paid and unpaid preferred stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount of Net Income (Loss) attributable to noncontrolling interest.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Amount of decrease to net income for accretion of temporary equity to its redemption value to derive net income apportioned to common stockholders.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Earnings Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Common Share
Net income (loss)	$ 280.3us-gaap_ProfitLoss	$ 252.8us-gaap_ProfitLoss	$ 319.2us-gaap_ProfitLoss	$ 324.1us-gaap_ProfitLoss	$ 250.4us-gaap_ProfitLoss	$ 259.1us-gaap_ProfitLoss	$ 236.6us-gaap_ProfitLoss	$ 190.0us-gaap_ProfitLoss	$ 1,176.4us-gaap_ProfitLoss	$ 936.1us-gaap_ProfitLoss	$ 825.4us-gaap_ProfitLoss
Subtract:
Net income (loss) attributable to noncontrolling interest									32.3	23.4	18.8
Preferred stock dividends									33.0us-gaap_DividendsPreferredStock	33.0us-gaap_DividendsPreferredStock	33.0us-gaap_DividendsPreferredStock
Adjustments to redemption amounts of redeemable noncontrolling interests									19.7
Total									$ 1,091.4	$ 879.7	$ 773.6
Weighted-average shares outstanding
Basic									294.7	294.6	297.5
Dilutive effects:
Stock options									1.8	1.6	1.0
Restricted stock units									1.8	1.7	1.5
Performance share awards									0.4	0.3	0.4
Diluted									298.7	298.2	300.4
Net income (loss) per common share:
Basic	$ 0.92us-gaap_EarningsPerShareBasic	$ 0.78us-gaap_EarningsPerShareBasic	$ 1.04us-gaap_EarningsPerShareBasic	$ 0.96us-gaap_EarningsPerShareBasic	$ 0.79us-gaap_EarningsPerShareBasic	$ 0.83us-gaap_EarningsPerShareBasic	$ 0.76us-gaap_EarningsPerShareBasic	$ 0.61us-gaap_EarningsPerShareBasic	$ 3.70us-gaap_EarningsPerShareBasic	$ 2.99us-gaap_EarningsPerShareBasic	$ 2.60us-gaap_EarningsPerShareBasic
Diluted	$ 0.91us-gaap_EarningsPerShareDiluted	$ 0.77us-gaap_EarningsPerShareDiluted	$ 1.03us-gaap_EarningsPerShareDiluted	$ 0.95us-gaap_EarningsPerShareDiluted	$ 0.78us-gaap_EarningsPerShareDiluted	$ 0.82us-gaap_EarningsPerShareDiluted	$ 0.75us-gaap_EarningsPerShareDiluted	$ 0.61us-gaap_EarningsPerShareDiluted	$ 3.65us-gaap_EarningsPerShareDiluted	$ 2.95us-gaap_EarningsPerShareDiluted	$ 2.58us-gaap_EarningsPerShareDiluted