Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets
Trade receivables, allowances	$ 23,720	$ 19,526
Property and equipment, accumulated depreciation	361,265	339,885
Identified intangibles, with finite useful lives, accumulated amortization	113,261	110,348
Investments in real estate ventures accounted for at fair value	$ 75,096	$ 63,579
Company shareholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	44,434,717	44,054,042
Common stock, shares outstanding (in shares)	44,434,717	44,054,042