Stock-Based Compensation Plans (Details 2) (Nonqualified Stock Options, USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Nonqualified Stock Options
Change in options outstanding
Options granted (in shares)	0.8
Assumptions used to estimate fair value of stock options granted during period
Weighted-average expected dividend yield (as a percent)	3.00%
Weighted-average expected volatility (as a percent)	53.30%
Weighted-average risk-free interest rate (as a percent)	1.10%
Weighted-average expected term	6 years 6 months
Weighted-average estimated fair value of stock options granted (in dollars per share)	$ 11.95
Other nonqualified stock option disclosures
Unrecognized compensation costs	$ 10.6
Weighted-average service period over which unrecognized compensation costs will be recognized	1 year 7 months 6 days

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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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 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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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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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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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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