Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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Share Repurchases (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		3 Months Ended
	Feb. 29, 2012	Oct. 31, 2011	Mar. 31, 2013
Class of Stock [Line Items]
Non-voting common stock repurchased	1,821,730
Share Repurchases (Textual) [Abstract]
Authorized a share repurchase program		$ 35.0
Common stock shares repurchased			955,342
Shares repurchased			0
Cost of common stock shares repurchased			29.2
Common Stock Non-Voting [Member]
Class of Stock [Line Items]
Non-voting common stock repurchased	1,821,730
Cost of non-voting common stock repurchased	52.9