Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Allowance for doubtful accounts	$ 6,212	$ 10,826
Equity:
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	180,000	180,000
Common stock, shares issued (in shares)	88,228	89,343
Common stock, shares outstanding (in shares)	88,228	89,343
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	500	500
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0