Consolidated Balance Sheet (Parenthetical) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts receivable, current	$ 11,314,000	$ 9,574,000
4.5% Mandatory Convertible Preferred Stock, Par or Stated Value Per Share (dollars per share)	$ 0.01	$ 0.01
4.5% Mandatory Convertible Preferred Stock, Shares Authorized	20,000,000	20,000,000
4.5% Mandatory Convertible Preferred Stock, shares issued	0	9,775,000
4.5% Mandatory Convertible Preferred Stock, shares outstanding	0	9,775,000
Mandatory redemption and aggregate liquidation value, 4.5% Mandatory Convertible Preferred Stock	$ 0	$ 977,500,000
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	360,536,659	333,771,660
Common stock, shares outstanding	360,536,659	333,771,660