Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 3,502	$ 3,700
Accumulated depreciation, property assets	$ 428,194	$ 433,935
Common stock - par value	$ 0.01	$ 0.01
Common stock - shares authorized	250,000,000	250,000,000
Common stock - shares issued	109,262,886	109,108,218
Treasury stock - shares at cost	56,369,752	56,369,752