Treasury Stock	3 Months Ended
Mar. 31, 2013
Equity [Abstract]
Treasury Stock	6. Treasury Stock During the three months ended March 31, 2013, pursuant to the Company’s share repurchase program, the Company repurchased 60,000 common shares at a weighted average price of $172.55 per share plus transaction costs for a total cost of approximately $10.4 million. During the three months ended March 31, 2012, the Company did not repurchase any common shares under the Company’s share repurchase program. The Company has repurchased a total of 305,000 shares of common stock at a weighted average price of $92.05 per share plus transaction costs for a total cost of $28.1 million under the share repurchase program. At March 31, 2013, there were 45,000 shares of common stock remaining authorized for repurchase under the share repurchase program.

Treasury Stock

3 Months Ended

Mar. 31, 2013

6. Treasury Stock

During the three months ended March 31, 2013, pursuant to the Company’s share repurchase program, the Company repurchased 60,000 common shares at a weighted average price of $172.55 per share plus transaction costs for a total cost of approximately $10.4 million. During the three months ended March 31, 2012, the Company did not repurchase any common shares under the Company’s share repurchase program. The Company has repurchased a total of 305,000 shares of common stock at a weighted average price of $92.05 per share plus transaction costs for a total cost of $28.1 million under the share repurchase program. At March 31, 2013, there were 45,000 shares of common stock remaining authorized for repurchase under the share repurchase program.