Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Summary of Shares Outstanding

The following table summarizes the shares outstanding for the three years ended December 31, 2016:

	Common Stock	Treasury Stock		Shares Outstanding
Balance, January 1, 2014	581,146,136	(303,853,372	)	277,292,764
Purchases	—	(7,626,382	)	(7,626,382	)
Issuances	—	2,298,184		2,298,184
Balance, December 31, 2014	581,146,136	(309,181,570	)	271,964,566
Purchases	—	(6,992,772	)	(6,992,772	)
Issuances	—	1,904,215		1,904,215
Balance, December 31, 2015	581,146,136	(314,270,127	)	266,876,009
Purchases	—	(10,725,869	)	(10,725,869	)
Issuances	—	1,180,020		1,180,020
Balance, December 31, 2016	581,146,136	(323,815,976	)	257,330,160