Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Common Stock Contingent Class A Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Noncontrolling Interests	Accumulated Other Comprehensive Income (Loss)	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings
Beginning Balance at Dec. 31, 2018	$ 1,056,799		$ 1,570	$ 212	$ 3,250	$ 285,071	$ (486)	$ 277,952	$ 489,230
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income	23,406							16,904	6,502
Dividends to common stockholders	(16,043)							(16,043)
Preferred dividend on exchangeable preferred partnership units								(3,224)	3,224
Earning distributions to limited partnership interests, redeemable partnership interests, and other noncontrolling interests	(27,280)								(27,280)
Grant of exchangeability, redemption and issuance	(15,530)		4			(572)			(14,962)
Issuance and redemption of limited partnership units including contingent units					(109)	109
Restricted stock units compensation	271					271
Other	(825)					(825)
Ending Balance at Mar. 31, 2019	1,020,798		1,574	212	3,141	284,054	(486)	275,589	456,714
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared and paid per share of common stock (dollars per share)		$ 0.09
Dividends declared per share of common stock (dollars per share)		0.10
Beginning Balance at Dec. 31, 2019	940,625		1,608	212	1,461	318,165	(34,894)	313,112	340,961		$ (19,023)	$ (19,023)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income	14,238							8,182	6,056
Other comprehensive income (loss), net of tax	(1,277)									$ (1,277)
Dividends to common stockholders	(17,773)							(17,773)
Preferred dividend on exchangeable preferred partnership units								(2,445)	2,445
Earning distributions to limited partnership interests, redeemable partnership interests, and other noncontrolling interests	(952)								(952)
Grant of exchangeability, redemption and issuance	1,989		4			4,423			(2,438)
Issuance and redemption of limited partnership units including contingent units	907				(411)	425			893
Restricted stock units compensation	2,199					1,804			395
Ending Balance at Mar. 31, 2020	$ 920,933		$ 1,612	$ 212	$ 1,050	$ 324,817	$ (34,894)	$ 282,053	$ 347,360	$ (1,277)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared and paid per share of common stock (dollars per share)		0.10
Dividends declared per share of common stock (dollars per share)		$ 0.10