Capital Stock (Tables)

12 Months Ended

Dec. 31, 2014

Class of Stock Disclosures [Abstract]

Common Shares Outstanding and Treasury Shares Held Rollforward Table

Common Shares Outstanding	Year Ended December 31,
	2014	2013	2012
At beginning of period	78,855,547	78,112,032	77,423,415
Exercise of common stock options, net	290,369	373,106	580,097
Grants of restricted stock, net	504,030	370,409	108,520
At end of period	79,649,946	78,855,547	78,112,032

Treasury Shares Held	Year Ended December 31,
	2014	2013	2012
At beginning of period	2,478,084	2,334,137	2,249,959
Shares received upon exercise of common stock options	189,469	119,477	81,616
Shares received upon vesting of restricted stock, net	5,377	24,470	2,562
At end of period	2,672,930	2,478,084	2,334,137