Stockholders' Equity (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Cash dividends
Record Date	Jul. 26, 2012
Payment Date	Aug. 09, 2012
Per Share Amount		$ 0.09	$ 0.09	$ 0.18	$ 0.18
Total Dividend Paid				$ 11,476	$ 11,596
Record Date Second February Two Thousand Twelve [Member]
Cash dividends
Record Date				Feb. 02, 2012
Payment Date				Feb. 16, 2012
Per Share Amount				$ 0.09
Total Dividend Paid				5,739
Record Date Twenty Six April Two Thousand Twelve [Member]
Cash dividends
Record Date				Apr. 26, 2012
Payment Date				May 10, 2012
Per Share Amount				$ 0.09
Total Dividend Paid				$ 5,737