Share Repurchase Program	6 Months Ended
Jun. 30, 2013
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. On June 18, 2013, the Board of Directors approved a continuation of the Share Repurchase Program for an additional $125,000 in repurchases of the Company's common stock. 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 six months ended June 30, 2013, an aggregate of 707,830 shares of the Company's common stock was repurchased under the program, at an average price per share of $46.29, for an aggregate purchase price of approximately $32,763. As of June 30, 2013, approximately $139,327 remained available for future repurchases under the Share Repurchase Program.

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. On June 18, 2013, the Board of Directors approved a continuation of the Share Repurchase Program for an additional $125,000 in repurchases of the Company's common stock. 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 six months ended June 30, 2013, an aggregate of 707,830 shares of the Company's common stock was repurchased under the program, at an average price per share of $46.29, for an aggregate purchase price of approximately $32,763. As of June 30, 2013, approximately $139,327 remained available for future repurchases under the Share Repurchase Program.