Repurchase of Common Stock (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2005	Oct. 13, 2008	Oct. 17, 2008	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2011	Jun. 30, 2011
Equity, Class of Treasury Stock [Line Items]
Interest rate of notes repurchased (in hundredths)	7.50%		4.50%					4.50%
Stock repurchase program, authorized amount		$ 9,864	$ 30,000
Value of repurchased principal				35,920	14,076
Repurchase value of repurchased pricipal	3,019			28,112	11,696		45,924
Stock repurchase program, remaining authorized repurchase amount	$ 18,304					$ 1,888