Stock Repurchases	12 Months Ended
Dec. 31, 2011
Stock Repurchases [Abstract]
Treasury Stock [Text Block]	Stock repurchases On April 19, 2011, ACI purchased 26,150,000 shares of its common stock held by the Estate at $17.50 per share, for a total of $457.6 million. The purchase was made pursuant to a definitive Stock Purchase Agreement (the “Purchase Agreement”) entered into by ACI and the Estate on March 25, 2011, following the execution of a binding letter agreement entered into on February 27, 2011. The shares purchased represented approximately 45% of ACI’s outstanding shares and 83% of the Estate’s holdings in the Company at the time of the purchase. On September 15, 2011, ACI’s Board of Directors approved the repurchase of up to $75 million of ACI’s common stock in a stock repurchase program. The program provides that the shares may be repurchased by the Company through September 30, 2014 in open market transactions or privately negotiated transactions at the Company’s discretion, subject to market conditions and other factors. The Company expects to fund repurchases using available cash and its existing senior credit facility. The Company is not obligated to purchase any shares under the stock repurchase program, and purchases may be discontinued, or the stock repurchase program may be modified or terminated, at any time. During the year ended December 31, 2011, the Company repurchased 0.3 million shares under the stock repurchase program for $5.2 million at an average price of $16.23 per share, exclusive of commissions paid. During the years ended December 31, 2010 and 2009, the Company did not repurchase any shares of common stock in open market transactions. The Company additionally received treasury shares in satisfaction of employees’ income tax withholding liability with respect to the settlement of certain restricted stock units. As of December 31, 2011, the aggregate cost of treasury shares received for these tax withholding obligations totaled $6.8 million. As of December 31, 2011, a total of 27.6 million treasury shares had been acquired at an aggregate cost of $487.2 million, an average of $17.65 per share.

Stock repurchases

On April 19, 2011, ACI purchased 26,150,000 shares of its common stock held by the Estate at $17.50 per share, for a total of $457.6 million. The purchase was made pursuant to a definitive Stock Purchase Agreement (the “Purchase Agreement”) entered into by ACI and the Estate on March 25, 2011, following the execution of a binding letter agreement entered into on February 27, 2011. The shares purchased represented approximately 45% of ACI’s outstanding shares and 83% of the Estate’s holdings in the Company at the time of the purchase.

On September 15, 2011, ACI’s Board of Directors approved the repurchase of up to $75 million of ACI’s common stock in a stock repurchase program. The program provides that the shares may be repurchased by the Company through September 30, 2014 in open market transactions or privately negotiated transactions at the Company’s discretion, subject to market conditions and other factors. The Company expects to fund repurchases using available cash and its existing senior credit facility. The Company is not obligated to purchase any shares under the stock repurchase program, and purchases may be discontinued, or the stock repurchase program may be modified or terminated, at any time. During the year ended December 31, 2011, the Company repurchased 0.3 million shares under the stock repurchase program for $5.2 million at an average price of $16.23 per share, exclusive of commissions paid. During the years ended December 31, 2010 and 2009, the Company did not repurchase any shares of common stock in open market transactions.

The Company additionally received treasury shares in satisfaction of employees’ income tax withholding liability with respect to the settlement of certain restricted stock units. As of December 31, 2011, the aggregate cost of treasury shares received for these tax withholding obligations totaled $6.8 million.

As of December 31, 2011, a total of 27.6 million treasury shares had been acquired at an aggregate cost of $487.2 million, an average of $17.65 per share.