Treasury Stock	6 Months Ended
Jun. 30, 2013
Equity [Abstract]
Treasury Stock	7. Treasury Stock During the six months ended June 30, 2013, pursuant to the Company’s share repurchase program, the Company repurchased 80,000 common shares at a weighted average price of $187.03 per share plus transaction costs for a total cost of approximately $15.0 million. During the six months ended June 30, 2012, the Company did not repurchase any common shares under the Company’s share repurchase program. The Company has repurchased a total of 325,000 shares of common stock at a weighted average price of $100.57 per share plus transaction costs for a total cost of $32.7 million under the share repurchase program. In May 2013, the Company’s board of directors authorized an extension of the share repurchase program to permit the purchase of 350,000 shares of common stock prior to May 21, 2016 in addition to the 25,000 shares remaining under the share repurchase program approved in the fourth quarter of 2010. At June 30, 2013, there were 375,000 shares of common stock remaining authorized for repurchase under the extended share repurchase program.

7. Treasury Stock

During the six months ended June 30, 2013, pursuant to the Company’s share repurchase program, the Company repurchased 80,000 common shares at a weighted average price of $187.03 per share plus transaction costs for a total cost of approximately $15.0 million. During the six months ended June 30, 2012, the Company did not repurchase any common shares under the Company’s share repurchase program. The Company has repurchased a total of 325,000 shares of common stock at a weighted average price of $100.57 per share plus transaction costs for a total cost of $32.7 million under the share repurchase program.

In May 2013, the Company’s board of directors authorized an extension of the share repurchase program to permit the purchase of 350,000 shares of common stock prior to May 21, 2016 in addition to the 25,000 shares remaining under the share repurchase program approved in the fourth quarter of 2010. At June 30, 2013, there were 375,000 shares of common stock remaining authorized for repurchase under the extended share repurchase program.