Capital Stock (Tables)

12 Months Ended

Dec. 31, 2015

Class of Stock Disclosures [Abstract]

Common Shares Outstanding and Treasury Shares Held Rollforward Table

Common Shares Outstanding	Year Ended December 31,
	2015	2014	2013
At beginning of period	79,649,946	78,855,547	78,112,032
Exercise of common stock options, net	67,808	290,369	373,106
Grants of restricted stock, net	538,916	504,030	370,409
At end of period	80,256,670	79,649,946	78,855,547

Treasury Shares Held	Year Ended December 31,
	2015	2014	2013
At beginning of period	2,672,930	2,478,084	2,334,137
Shares received upon exercise of common stock options	36,818	189,469	119,477
Shares received upon vesting of restricted stock, net	57,210	5,377	24,470
At end of period	2,766,958	2,672,930	2,478,084