Capital Stock (Tables)

12 Months Ended

Dec. 31, 2016

Class of Stock Disclosures [Abstract]

Common Shares Outstanding and Treasury Shares Held Rollforward Table

Common Shares Outstanding	Year Ended December 31,
	2016	2015	2014
At beginning of period	80,256,544	79,649,946	78,855,547
Exercise of common stock options, net	636,937	67,808	290,369
Grants of restricted stock, net	281,591	538,790	504,030
Issuance of common stock	33,810,000	—	—
At end of period	114,985,072	80,256,544	79,649,946

Treasury Shares Held	Year Ended December 31,
	2016	2015	2014
At beginning of period	2,767,084	2,672,930	2,478,084
Shares received upon exercise of common stock options	13,854	36,818	189,469
Shares received upon vesting of restricted stock, net	85,053	57,336	5,377
At end of period	2,865,991	2,767,084	2,672,930