CONSOLIDATED BALANCE SHEETS Balance Sheet Parenthetical (USD $)	Mar. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable, Current	$ 21,482,000	$ 22,212,000
Preferred Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Common Stock, Shares Authorized	125,000,000	125,000,000
Common Stock, Shares, Issued	59,695,646	59,600,713
Common Stock, Shares, Outstanding	57,113,126	57,026,957
Treasury Stock, Shares	2,582,520	2,582,520