Stockholders' Equity (Details) (USD $)	1 Months Ended					3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2012	Aug. 31, 2012	Jul. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2010	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2008	Jan. 25, 2008
Summary of changes in stockholders' equity [Roll Forward]
Balance at beginning of period									$ 249,195,000
Net Income						1,782,000	2,850,000		10,422,000	29,768,000
Dividend Payments									(6,612,000)
Unrealized Foreign Currency Translation Gain						143,000	(150,000)		64,000	(76,000)
Unrealized Holding Gain on Marketable Securities						211,000	(103,000)		399,000	(20,000)
Net Change in Fair Value of Derivatives						(149,000)	(843,000)		(79,000)	(440,000)
Share-based compensation expense (net of forfeited shares)									222,000
Balance at end of period	253,611,000					253,611,000			253,611,000
Stock Repurchase Program [Abstract]
Shares authorized for repurchase (in shares)												1,000,000
Total number of shares purchased (in shares)	0	0	0					223,051			491,572
Payments for shares purchased								5,200,000			11,500,000
Average Price Paid per Share (in dollars per share)	0	0	0
Total Number of Shares Purchased as Part of Publicly Announced Plan (in shares)	0	0	0
Maximum Number of Shares that May Yet Be Purchased Under the Plan (in shares)	285,377	285,377	285,377			285,377			285,377
Dividend Payments [Abstract]
Record Date	Aug. 16, 2012			May 16, 2012	Feb. 15, 2012
Payment Date	Sep. 04, 2012			Jun. 01, 2012	Mar. 01, 2012
Per Share Amount (in dollars per share)	$ 0.250			$ 0.250	$ 0.375
Total Dividend Paid	1,801,000			1,801,000	2,690,000				6,612,000	8,303,000
Payment of cash dividends related to unvested stock awards									314,000
Total dividends paid, excluding dividends related to unvested stock awards									6,292,000
Dividends related to unvested stock awards	$ 6,000					$ 6,000			$ 6,000