Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Common Stock
Common Stock, Par Value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized (in shares)	1,280,000,000	1,280,000,000
Common Stock, Shares Issued (in shares)	579,597,990	578,827,768
Treasury Stock (in shares)
Common Stock Held in Treasury, Shares	410,969	350,961