CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts	$ 12,890	$ 12,083
Preferred stock, issued	0	0
Common stock, shares issued	93,471,774	94,831,377
Common stock, shares outstanding	93,471,774	94,831,377
Common stock, par value	$ 0.01	$ 0.01