Share Repurchase Program	3 Months Ended
Mar. 31, 2014
Equity [Abstract]
Share Repurchase Program [Text Block]	Share Repurchase Program The Company's Board of Directors authorized a share repurchase program (the “Share Repurchase Program”), effective as of January 1, 2004, originally providing for share repurchases in the aggregate amount of $20,000. The Share Repurchase Program does not have a fixed expiration or termination date and may be modified or terminated by the Board of Directors at any time. On several occasions the Board of Directors has increased the amount authorized for repurchase. The Share Repurchase Program permits the Company to effect repurchases from time to time through a combination of open market repurchases or in privately negotiated transactions at such prices and times as are determined to be in the best interest of the Company. During the three months ended March 31, 2014, an aggregate of 850,935 shares of the Company's common stock was repurchased, in the open market, under the program, at an average price per share of $34.48, for an aggregate purchase price of approximately $29,336. As of March 31, 2014, approximately $40,582 remained available for future repurchases under the Share Repurchase Program. Subsequent to the end of the quarter, on April 29, 2014, the Board of Directors approved the continuation of the Company's Share Repurchase Program for up to $150,000 in repurchases of the Company's common stock which includes amounts remaining under the prior authorization.

Share Repurchase Program

The Company's Board of Directors authorized a share repurchase program (the “Share Repurchase Program”), effective as of January 1, 2004, originally providing for share repurchases in the aggregate amount of $20,000. The Share Repurchase Program does not have a fixed expiration or termination date and may be modified or terminated by the Board of Directors at any time. On several occasions the Board of Directors has increased the amount authorized for repurchase. The Share Repurchase Program permits the Company to effect repurchases from time to time through a combination of open market repurchases or in privately negotiated transactions at such prices and times as are determined to be in the best interest of the Company. During the three months ended March 31, 2014, an aggregate of 850,935 shares of the Company's common stock was repurchased, in the open market, under the program, at an average price per share of $34.48, for an aggregate purchase price of approximately $29,336. As of March 31, 2014, approximately $40,582 remained available for future repurchases under the Share Repurchase Program. Subsequent to the end of the quarter, on April 29, 2014, the Board of Directors approved the continuation of the Company's Share Repurchase Program for up to $150,000 in repurchases of the Company's common stock which includes amounts remaining under the prior authorization.