Transactions With Related Parties (Details) (USD $)	3 Months Ended
	Mar. 31, 2012 Y	Mar. 31, 2011	Dec. 31, 2011
Related Party Transaction [Line Items]
Number of independent directors	4
Management Agreement initial expiration date	February 23, 2015
Management Agreement additional term of expiration (in years)	1
Proportion of average annual management fee	4
Prior notice for uncertain termination (in days)	180
Period of annual management fees earned (in years)	2
Management fee	$ 3,842,000	$ 3,092,000
Management fee payable	1,696,000		1,200,000
Company's Equity Up To $250 Million [Member]
Related Party Transaction [Line Items]
Management fee bases per annum	1.50%
Company's Equity In Excess Of $250 Million And Up To $500 Million [Member]
Related Party Transaction [Line Items]
Management fee bases per annum	1.10%
Company's Equity In Excess Of $500 Million And Up To $750 Million [Member]
Related Party Transaction [Line Items]
Management fee bases per annum	0.80%
Company's Equity In Excess Of $750 [Member]
Related Party Transaction [Line Items]
Management fee bases per annum	0.50%
Minimum [Member] | Company's Equity In Excess Of $250 Million And Up To $500 Million [Member]
Related Party Transaction [Line Items]
Management fee payable	250,000,000
Minimum [Member] | Company's Equity In Excess Of $500 Million And Up To $750 Million [Member]
Related Party Transaction [Line Items]
Management fee payable	500,000,000
Minimum [Member] | Company's Equity In Excess Of $750 [Member]
Related Party Transaction [Line Items]
Management fee payable	750,000,000
Maximum [Member] | Company's Equity Up To $250 Million [Member]
Related Party Transaction [Line Items]
Management fee payable	250,000,000
Maximum [Member] | Company's Equity In Excess Of $250 Million And Up To $500 Million [Member]
Related Party Transaction [Line Items]
Management fee payable	500,000,000
Maximum [Member] | Company's Equity In Excess Of $500 Million And Up To $750 Million [Member]
Related Party Transaction [Line Items]
Management fee payable	$ 750,000,000