Shareholders' Equity

12 Months Ended

Dec. 31, 2017

Stockholders' Equity Note [Abstract]

Shareholders' equity

Shareholders’ equity

Our declared quarterly cash dividends totaled $110.0 million, $122.2 million, and $117.9 million in 2017, 2016, and 2015, respectively. Under the share repurchase program authorized by our Board of Directors, we repurchased 35.4 million, 30.9 million, and 21.2 million shares in 2017, 2016, and 2015, respectively, for a total of $910.3 million, $600.0 million, and $433.7 million in 2017, 2016, and 2015, respectively. At December 31, 2017, we had remaining authorization to repurchase $94.4 million of common shares. On January 25, 2018 our Board of Directors increased our repurchase authorization by $500.0 million.

Under our stock-based compensation plans, we accept shares as payment under certain conditions related to stock option exercises and vesting of restricted shares and share units, generally related to the payment of tax obligations. During 2017, 2016, and 2015, employees surrendered shares valued at $6.0 million, $3.2 million, and $9.0 million, respectively, under these plans. Such share transactions are excluded from the above noted share repurchase authorization.