Common Stock	3 Months Ended
Mar. 31, 2018
Stockholders' Equity Note [Abstract]
Common Stock	Common Stock As of March 31, 2018 and December 31, 2017, there were 58,450,685 and 58,798,428 shares of our common stock outstanding, respectively. During the three months ended March 31, 2018 and 2017, we issued 98,153 and 117,034 shares of common stock, respectively, primarily upon: (a) the satisfaction of required conditions under certain of our share-based compensation plans and (b) the purchase of common stock pursuant to our employee stock purchase plan. On September 26, 2011, our Board of Directors authorized us to repurchase up to $100.0 million of our outstanding common stock. On December 5, 2013, October 23, 2014, October 28, 2015 and October 25, 2017, our Board of Directors authorized us to repurchase up to an additional $100.0 million, $250.0 million, $200.0 million and $100.0 million of our outstanding common stock, respectively. During 2018, we have repurchased approximately 445,896 shares of our common stock for approximately $34.5 million. Since the inception of the repurchase programs through March 31, 2018, we have repurchased approximately 13.3 million shares of our common stock for approximately $609.7 million. As of March 31, 2018, there remained authorization for us to repurchase approximately $140.3 million of our shares. The repurchase programs have no expiration date and do not obligate the Company to acquire any particular amount of common stock and may be suspended, recommenced or discontinued at any time or from time to time without prior notice. We may repurchase our shares from time to time to the extent permitted by securities laws and other legal requirements, including provisions in our 2016 Credit Agreement placing limitations on such repurchases. The repurchase programs have been and will be funded from our operations.

Common Stock

As of March 31, 2018 and December 31, 2017, there were 58,450,685 and 58,798,428 shares of our common stock outstanding, respectively.

During the three months ended March 31, 2018 and 2017, we issued 98,153 and 117,034 shares of common stock, respectively, primarily upon: (a) the satisfaction of required conditions under certain of our share-based compensation plans and (b) the purchase of common stock pursuant to our employee stock purchase plan.

On September 26, 2011, our Board of Directors authorized us to repurchase up to $100.0 million of our outstanding common stock. On December 5, 2013, October 23, 2014, October 28, 2015 and October 25, 2017, our Board of Directors authorized us to repurchase up to an additional $100.0 million, $250.0 million, $200.0 million and $100.0 million of our outstanding common stock, respectively. During 2018, we have repurchased approximately 445,896 shares of our common stock for approximately $34.5 million. Since the inception of the repurchase programs through March 31, 2018, we have repurchased approximately 13.3 million shares of our common stock for approximately $609.7 million. As of March 31, 2018, there remained authorization for us to repurchase approximately $140.3 million of our shares. The repurchase programs have no expiration date and do not obligate the Company to acquire any particular amount of common stock and may be suspended, recommenced or discontinued at any time or from time to time without prior notice. We may repurchase our shares from time to time to the extent permitted by securities laws and other legal requirements, including provisions in our 2016 Credit Agreement placing limitations on such repurchases. The repurchase programs have been and will be funded from our operations.