Capital Stock (Tables)

12 Months Ended

Dec. 31, 2018

Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]

Common Shares Outstanding and Treasury Shares Held Rollforward Table

Common Shares Outstanding	Year Ended December 31,
	2018	2017	2016
At beginning of period	115,877,704	114,985,072	80,256,544
Exercise of common stock options, net	65,524	—	636,937
Grants of restricted stock, net	2,022,316	892,632	281,591
Issuance of common stock	7,772,021	—	33,810,000
At end of period	125,737,565	115,877,704	114,985,072

Treasury Shares Held	Year Ended December 31,
	2018	2017	2016
At beginning of period	2,638,093	2,536,421	2,281,495
Shares received upon exercise of common stock options	—	—	13,854
Shares received upon vesting of restricted stock, net	79,476	101,672	241,072
At end of period	2,717,569	2,638,093	2,536,421