Consolidated Statement Of Changes In Equity (USD $) In Thousands, unless otherwise specified		Total		Parent [Member]	Noncontrolling Interest [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2011		$ 370,916
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2011					0
Stockholders' Equity Attributable to Parent at Dec. 31, 2011				370,916
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net investment income		19,782
Net realized gain (loss) on investments and financial derivatives		(23,068)
Change in net unrealized gain (loss) on investments and financial derivatives		46,109
Net Income (Loss) Attributable to Parent		42,823		42,823
Net Income (Loss) Attributable to Noncontrolling Interest		0			0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		42,823
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Proceeds from the issuance of shares		0		0
Shares issued in connection with incentive fee payment		0		0
Noncontrolling Interest, Increase from Equity Issuance or Sale of Parent Equity Interest		0			0
Dividends(1)	[1]	(18,522)	[2]	(18,522)	0
Offering costs		0		0
Share-based LTIP awards		58		58	0
Net increase (decrease) in equity from transactions		(18,464)		(18,464)	0
Net increase in equity		24,359		24,359	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2012		395,275
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2012					0
Stockholders' Equity Attributable to Parent at Jun. 30, 2012				395,275
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2012		506,355
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2012		0			0
Stockholders' Equity Attributable to Parent at Dec. 31, 2012		506,355		506,355
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net investment income		22,737
Net realized gain (loss) on investments and financial derivatives		18,264
Change in net unrealized gain (loss) on investments and financial derivatives		11,450
Net Income (Loss) Attributable to Parent		51,935		51,935
Net Income (Loss) Attributable to Noncontrolling Interest		516			516
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		52,451
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Proceeds from the issuance of shares		125,600		125,600
Shares issued in connection with incentive fee payment		941		941
Noncontrolling Interest, Increase from Equity Issuance or Sale of Parent Equity Interest		4,664			4,664
Dividends(1)	[1]	(51,976)	[2]	(51,491)	(485)
Offering costs		(262)		(262)
Share-based LTIP awards		85		84	1
Net increase (decrease) in equity from transactions		79,052		74,872	4,180
Net increase in equity		131,503		126,807	4,696
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2013		637,858
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2013		4,696			4,696
Stockholders' Equity Attributable to Parent at Jun. 30, 2013		$ 633,162		$ 633,162

[1] For the six month periods ended June 30, 2013 and 2012, dividends totaling $2.29 and $1.10, respectively, per common share and convertible unit outstanding were declared and paid.

[2] The Company pays quarterly dividends in arrears, so a portion of the dividends paid in each calendar year relate to the prior year's earnings.