Segment Information (Schedule of Revenue from External Customers, by Geographical Areas) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net Operating Revenue	$ 17,745	$ 18,723	$ 17,791	$ 17,569	$ 17,603	$ 18,146	$ 18,002	$ 17,115	$ 71,828	$ 70,866
United States [Member]
Segment Reporting Information [Line Items]
Net Operating Revenue									30,432	30,215
Canada [Member]
Segment Reporting Information [Line Items]
Net Operating Revenue									34,465	34,112
International Waters [Member]
Segment Reporting Information [Line Items]
Net Operating Revenue									6,601	6,132
Aruba [Member]
Segment Reporting Information [Line Items]
Net Operating Revenue									322	407
International [Member]
Segment Reporting Information [Line Items]
Net Operating Revenue									$ 41,396	$ 40,651