CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 19,134	$ 19,443
Intangible assets, accumulated amortization	$ 88,098	$ 64,215
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	120,000,000	120,000,000
Common stock, issued	85,500,037	85,987,883
Common stock, outstanding	85,500,037	85,987,883