Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 374	$ 246
Common stock - Class A, par value	$ 0.01	$ 0.01
Common stock - Class A, shares authorized	400,000	400,000
Common stock - Class A, shares issued	127,784	126,933
Common stock - Class A, shares outstanding	127,784	126,933