Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Allowances for accounts receivable	$ 28,600	$ 17,700
Preferred stock, par value (USD per share)	$ 1	$ 1
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 value (USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, share issued	66,590,875	56,153,140
Common stock, shares outstanding	64,397,893	53,960,158
Treasury stock	2,192,982	2,192,982