Stock Compensation Plans - Summary of Stock Option Compensation Awards Outstanding and Exercisable (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013
Summary of stock compensation awards outstanding and exercisable [Abstract]
Number of Awards outstanding, Ending balance (in shares)	1,458,802
Weighted Average Exercise Price Awards outstanding, Ending balance (in dollars per share)	$ 26.99
Intrinsic Value Awards outstanding, Ending balance	$ 10.2
Weighted Average Remaining Contractual Life Awards outstanding, Ending balance	7 years 0 months 18 days
Number of Awards exercisable, Ending balance (in shares)	834,737
Weighted Average Exercise Price Awards exercisable, Ending balance (in dollars per share)	$ 24.57
Intrinsic Value Awards exercisable, Ending balance	$ 7.9
Weighted Average Remaining Contractual Life Awards exercisable, Ending balance	6 years 0 months 25 days

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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