Stockholder's Equity (Schedule of Common Stock Activity) (Details)	9 Months Ended
	Sep. 30, 2017 shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock – December 31, 2016 (in shares)	202,087,672
Common Stock – December 31, 2016, Issued (in shares)	206,182,213
Restricted stock issued (in shares)	1,216,585
Repurchase of common stock (in shares)	(71,476,417)
Shares held to cover taxes on vesting restricted shares and other (in shares)	(498,111)
Employee stock purchase plan participation (in shares)	41,074
Common Stock – September 30, 2017, Issued (in shares)	207,439,872
Common Stock – September 30, 2017 (in shares)	131,370,803
Issued
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock – December 31, 2016, Issued (in shares)	206,182,213
Restricted stock issued (in shares)	1,216,585
Employee stock purchase plan participation (in shares)	41,074
Common Stock – September 30, 2017, Issued (in shares)	207,439,872
Less Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock – December 31, 2016 (in shares)	(4,094,541)
Repurchase of common stock (in shares)	(71,476,417)
Shares held to cover taxes on vesting restricted shares and other (in shares)	(498,111)
Common Stock – September 30, 2017 (in shares)	(76,069,069)