Annual report pursuant to Section 13 and 15(d)

Intangible Assets and Goodwill (Details Textual)

v2.4.0.6
Intangible Assets and Goodwill (Details Textual) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Intangible Assets and Goodwill (Textual) [Abstract]      
Net of accumulated impairment losses $ 796,725,000    
Definite lived intangible assets, amortization expense 1,600,000 1,700,000 1,700,000
Weighted-average amortization period 15 years    
Goodwill impairment $ 0 $ 0 $ 0
Lease agreements [Member]
     
Intangible Assets and Goodwill (Textual) [Abstract]      
Weighted-average amortization period 15 years