Consolidated Statement Of Changes In Equity - USD ($) $ in Thousands		Total		Parent [Member]	Noncontrolling Interest [Member]
Stockholders' Equity Attributable to Parent at Dec. 31, 2015				$ 732,049
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2015					$ 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		26,738
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		(37,291)
Change in net unrealized gain (loss) on investments, financial derivatives, and foreign currency translation		(7,080)
Net Income (Loss) Attributable to Parent		(17,699)		(17,699)
Net Income (Loss) Attributable to Noncontrolling Interest		66			66
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(17,633)
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Contributions from non-controlling interests		4,747			4,747
Dividends	[1]	(50,256)	[2]	(49,938)	(318)
Distributions to non-controlling interest		(2,560)			(2,560)
Adjustment to non-controlling interest		0		(10)	10
Shares repurchased		(8,797)		(8,797)
Share-based LTIP awards		300		298	2
Net increase (decrease) in equity from transactions		(56,566)		(58,447)	1,881
Net increase (decrease) in equity		(74,199)		(76,146)	1,947
Stockholders' Equity Attributable to Parent at Sep. 30, 2016				655,903
Stockholders' Equity Attributable to Noncontrolling Interest at Sep. 30, 2016					8,850
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Sep. 30, 2016		664,753
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
CHANGE IN SHAREHOLDERS’ EQUITY RESULTING FROM OPERATIONS
Net investment income		28,109
Net realized gain (loss) on investments, financial derivatives, and foreign currency transactions		(4,973)
Change in net unrealized gain (loss) on investments, financial derivatives, and foreign currency translation		4,630
Net Income (Loss) Attributable to Parent		26,537		26,537
Net Income (Loss) Attributable to Noncontrolling Interest		1,229			1,229
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		27,766
CHANGE IN EQUITY RESULTING FROM TRANSACTIONS
Contributions from non-controlling interests		14,201			14,201
Dividends	[1]	(44,336)	[2]	(44,050)	(286)
Distributions to non-controlling interest		(8,178)			(8,178)
Adjustment to non-controlling interest		0		(6)	6
Shares repurchased		(4,791)		(4,791)
Share-based LTIP awards		285		284	1
Net increase (decrease) in equity from transactions		(42,819)		(48,563)	5,744
Net increase (decrease) in equity		(15,053)		(22,026)	6,973
Stockholders' Equity Attributable to Parent at Sep. 30, 2017		615,635		$ 615,635
Stockholders' Equity Attributable to Noncontrolling Interest at Sep. 30, 2017		14,089			$ 14,089
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Sep. 30, 2017		$ 629,724

[1] For the nine month periods ended September 30, 2017 and 2016, dividends totaling $1.35 and $1.50 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.