Consolidated Statement Of Changes In Equity - USD ($) $ in Thousands		Total		Parent [Member]	Noncontrolling Interest [Member]
Stockholders' Equity Attributable to Parent at Dec. 31, 2013				$ 620,401
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2013					$ 5,648
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2013		$ 626,049
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net investment income		58,751
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		4,162
Change in net unrealized gain (loss) on investments, financial derivatives, and foreign currency translation		(2,964)
Net Income (Loss) Attributable to Parent		59,167		59,167
Net Income (Loss) Attributable to Noncontrolling Interest		782			782
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		59,949
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Proceeds from the issuance of shares	[1]	188,400		188,400
Shares issued in connection with incentive fee payment		449		449
Contributions from non-controlling interests		1,793			1,793
Dividends	[2]	(86,449)	[3]	(85,796)	(653)
Distributions to non-controlling interest		(1,667)			(1,667)
Adjustment to non-controlling interest		0		(484)	484
Offering costs		(247)		(247)
Shares repurchased		0		0
Share-based LTIP awards		267		265	2
Net increase (decrease) in equity from transactions		102,546		102,587	(41)
Net increase (decrease) in equity		162,495		161,754	741
Stockholders' Equity Attributable to Parent at Dec. 31, 2014				782,155
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2014					6,389
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2014		788,544
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net investment income		66,176
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		20,953
Change in net unrealized gain (loss) on investments, financial derivatives, and foreign currency translation		(48,700)
Net Income (Loss) Attributable to Parent		38,089		38,089
Net Income (Loss) Attributable to Noncontrolling Interest		340			340
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		38,429
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Proceeds from the issuance of shares	[1]	0		0
Shares issued in connection with incentive fee payment		0		0
Contributions from non-controlling interests		2,153			2,153
Dividends	[2]	(83,460)	[3]	(82,940)	(520)
Distributions to non-controlling interest		(1,468)			(1,468)
Adjustment to non-controlling interest		0		(6)	6
Offering costs		0		0
Shares repurchased		(5,639)		(5,639)
Share-based LTIP awards		393		390	3
Net increase (decrease) in equity from transactions		(88,021)		(88,195)	174
Net increase (decrease) in equity		(49,592)		(50,106)	514
Stockholders' Equity Attributable to Parent at Dec. 31, 2015		732,049		732,049
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2015		6,903			6,903
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2015		738,952
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net investment income		35,765
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		(39,533)
Change in net unrealized gain (loss) on investments, financial derivatives, and foreign currency translation		(11,934)
Net Income (Loss) Attributable to Parent		(16,007)		(16,007)
Net Income (Loss) Attributable to Noncontrolling Interest		305			305
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(15,702)
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Proceeds from the issuance of shares	[1]	0		0
Shares issued in connection with incentive fee payment		0		0
Contributions from non-controlling interests		5,552			5,552
Dividends	[2]	(65,148)	[3]	(64,735)	(413)
Distributions to non-controlling interest		(5,249)			(5,249)
Adjustment to non-controlling interest		0		(15)	15
Offering costs		0		0
Shares repurchased		(14,028)		(14,028)
Share-based LTIP awards		400		397	3
Net increase (decrease) in equity from transactions		(78,473)		(78,381)	(92)
Net increase (decrease) in equity		(94,175)		(94,388)	213
Stockholders' Equity Attributable to Parent at Dec. 31, 2016		637,661		$ 637,661
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2016		7,116			$ 7,116
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2016		$ 644,777

[1] For the year ended December 31, 2014 proceeds from the issuance of shares is net of an underwriters' discount of $3.0 million.

[2] For the years ended December 31, 2016, 2015, and 2014, dividends totaling $1.95, $2.45, and $3.08, respectively, per common share and convertible unit outstanding, were declared and paid.

[3] 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.