Shareholders' Equity	12 Months Ended
Dec. 31, 2017
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity During the fourth and third quarters of 2017, we declared a cash dividend on our common stock of $0.60 per share which was paid in the first quarter of 2018 and fourth quarter of 2017, respectively. During the first and second quarters of 2017, we declared a cash dividend on our common stock of $0.48 per share which was paid in the second and third quarters of 2017, respectively. During the fourth and third quarters of 2016, we declared a cash dividend on our common stock of $0.48 per share which was paid in the first quarter of 2017 and fourth quarter of 2016, respectively. We also declared and paid a cash dividend on our common stock of $0.375 per share during each of the first and second quarters of 2016. During the first quarter of 2016, we also paid a cash dividend on our common stock of $0.375 per share which was declared during the fourth quarter of 2015. In April 2017, our board of directors authorized a 12-month common stock repurchase program for up to $500 million. The timing and number of shares to be repurchased will depend on a variety of factors including price and market conditions. Repurchases under the program may be made at management's discretion from time to time on the open market or through privately negotiated transactions. During the year ended December 31, 2017, we repurchased 1.8 million shares of our common stock for a total of $225.0 million in open market transactions that were recorded within Treasury stock in our consolidated balance sheets. As of December 31, 2017, we have $275.0 million that remain available for future stock repurchase transactions under our Board approved program. During February 2018, we repurchased an additional 1.5 million shares for a total of $186.4 million in open market transactions. During the fourth quarter of 2015, our board of directors authorized a common stock repurchase program for up to $500 million that was completed in August 2016. During 2016, we purchased 4.1 million shares for a total of $300.0 million in open market transactions. These transactions were recorded within Treasury stock in our consolidated balance sheet. Our repurchases under this program, including the 2.1 million shares repurchased for $200.0 million during the fourth quarter of 2015, totaled $500.0 million.

Shareholders' Equity

During the fourth and third quarters of 2017, we declared a cash dividend on our common stock of $0.60 per share which was paid in the first quarter of 2018 and fourth quarter of 2017, respectively. During the first and second quarters of 2017, we declared a cash dividend on our common stock of $0.48 per share which was paid in the second and third quarters of 2017, respectively.

During the fourth and third quarters of 2016, we declared a cash dividend on our common stock of $0.48 per share which was paid in the first quarter of 2017 and fourth quarter of 2016, respectively. We also declared and paid a cash dividend on our common stock of $0.375 per share during each of the first and second quarters of 2016. During the first quarter of 2016, we also paid a cash dividend on our common stock of $0.375 per share which was declared during the fourth quarter of 2015.

In April 2017, our board of directors authorized a 12-month common stock repurchase program for up to $500 million. The timing and number of shares to be repurchased will depend on a variety of factors including price and market conditions. Repurchases under the program may be made at management's discretion from time to time on the open market or through privately negotiated transactions. During the year ended December 31, 2017, we repurchased 1.8 million shares of our common stock for a total of $225.0 million in open market transactions that were recorded within Treasury stock in our consolidated balance sheets. As of December 31, 2017, we have $275.0 million that remain available for future stock repurchase transactions under our Board approved program.

During February 2018, we repurchased an additional 1.5 million shares for a total of $186.4 million in open market transactions.

During the fourth quarter of 2015, our board of directors authorized a common stock repurchase program for up to $500 million that was completed in August 2016. During 2016, we purchased 4.1 million shares for a total of $300.0 million in open market transactions. These transactions were recorded within Treasury stock in our consolidated balance sheet. Our repurchases under this program, including the 2.1 million shares repurchased for $200.0 million during the fourth quarter of 2015, totaled $500.0 million.