Marketable Securities (Details) (SHG, USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2005 person	Mar. 31, 2012 person	Dec. 31, 2011
SHG
Marketable Securities
Investment in senior subordinated notes of related party		$ 6,500,000	$ 6,500,000
Face rate of senior subordinated notes (as a percent)		11.00%	11.00%
Effective yield on senior subordinated notes (as a percent)		11.10%	11.10%
Number of directors serving as chief executive officer of related entity	1	1