CONSOLIDATED STATEMENTS OF COMPRHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Consolidated net income attributable to common stockholders	$ 34,705	$ 28,340	$ 28,927
Other comprehensive income/(loss):
Net unrealized income/(loss) on investments, net of non-controlling interest	1,852	(152)	(233)
Cumulative reversal of accumulated other comprehensive income due to sale of securities	0	(190)	0
Income tax expense related to items of other comprehensive income	0	0	0
Comprehensive income	$ 36,557	$ 27,998	$ 28,694