Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019		Mar. 31, 2018
Net increase (decrease) in shareholders' equity resulting from operations
Net income (loss) attributable to common stockholders	$ 15,408		$ 21,039
Add: Net income (loss) attributable to Convertible Non-controlling Interests	380		142
Net income (loss) related to common stockholders and Convertible Non-controlling Interests	15,788		21,181
Dividends Paid:
Dividends	(16,764)	[1]	(12,850)
Undistributed (Distributed in excess of) earnings:
Total undistributed (distributed in excess of) earnings	$ (976)		$ (8,331)
Basic earnings per share of common stock:
Distributed (in usd per share)	$ 0.55		$ 0.41
Undistributed (Distributed in excess of) (in usd per share)	(0.03)		0.26
Basic earnings per common share (in usd per share)	0.52		0.67
Diluted earnings per share of common stock:
Distributed (in usd per share)	0.55		0.41
Undistributed (Distributed in excess of) (usd per share)	(0.03)		0.26
Diluted earnings per common share (in usd per share)	$ 0.52		$ 0.67
Net increase (decrease) in equity resulting from operations	$ 700		$ 100
Common Stock
Net increase (decrease) in shareholders' equity resulting from operations
Net income (loss) attributable to common stockholders			20,709
Dividends Paid:
Dividends	(16,360)		(12,562)
Undistributed (Distributed in excess of) earnings:
Total undistributed (distributed in excess of) earnings	$ (952)		$ (8,147)
Weighted average shares outstanding (basic and diluted):
Weighted average shares outstanding (basic and diluted) (in shares)	29,747,537		30,830,615
Long-Term Incentive Plan Units [Member]
Net increase (decrease) in shareholders' equity resulting from operations
Net income (loss) attributable to common stockholders			$ 330
Dividends Paid:
Dividends			(201)
Undistributed (Distributed in excess of) earnings:
Total undistributed (distributed in excess of) earnings			$ (129)
Weighted average shares outstanding (basic and diluted):
Weighted average shares outstanding (basic and diluted) (in shares)			491,638
Non-controlling Interest
Dividends Paid:
Dividends	$ (404)		$ (87)
Undistributed (Distributed in excess of) earnings:
Total undistributed (distributed in excess of) earnings	$ (24)		$ (55)
Weighted average shares outstanding (basic and diluted):
Weighted average shares outstanding (basic and diluted) (in shares)	733,371		212,000
Convertible Non-controlling Interest [Member]
Weighted average shares outstanding (basic and diluted):
Weighted average shares outstanding (basic and diluted) (in shares)	30,480,908

[1] For the three-month period ended March 31, 2019, dividends totaling $0.55 per share of common stock outstanding were declared.