Segment Data (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Total assets	$ 438,051,000	$ 467,321,000	$ 490,810,000
Segment Data (Textual) [Abstract]
Significant sources of revenue generated outside	0	0	0
Mexico [Member]
Segment Reporting Information [Line Items]
Total assets	$ 10,500,000	$ 10,600,000