Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Stockholders' Equity Note [Abstract]

Schedule of Stockholders Equity

The following table summarizes the changes in shares of Common Stock outstanding and Treasury Stock:

	Common Stock Outstanding		Treasury Stock
Balance at December 31, 2015	195,521,208		127,816,704
Repurchases of common stock	(10,633,235	)	10,633,235
Issuance of common stock	767,060		(767,060	)
Conversions to common stock	13,685		(13,685	)
Balance at December 31, 2016	185,668,718		137,669,194
Issuance of common stock	881,480		(881,480	)
Conversions to common stock	53,540		(53,540	)
Balance at December 31, 2017	186,603,738		136,734,174
Issuance of common stock	1,043,809		(1,043,809	)
Conversions to common stock	27,535		(27,535	)
Balance at December 31, 2018	187,675,082		135,662,830