Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 75,544	$ 63,787
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	700,000,000	700,000,000
Common stock, shares issued (in shares)	134,114,715	132,596,758
Common stock, shares outstanding (in shares)	134,114,715	132,596,758
Select
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 75,544	$ 63,787
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares issued (in shares)	100	100
Common stock, shares outstanding (in shares)	100	100