Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total		Class A Common Stock	Class B Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid- in-Capital	Treasury Stock	Retained Earnings (Dividends in Excess of Earnings)	Accumulated Other Comprehensive Income (Loss)	Operating Partnership	Consolidated Joint Ventures
Beginning Balance (in shares) at Dec. 31, 2017					93,641,000	17,668,000
Beginning Balance at Dec. 31, 2017	$ 1,488,146				$ 94	$ 18	$ 1,306,136	$ (31,956)	$ (39,112)	$ (212)	$ 240,861	$ 12,317
Increase Decrease in Stockholders' Equity
Contributions	5,040											5,040
Distributions	(22,691)										(8,899)	(13,792)
Amortization of equity based compensation	4,505						4,505
Grants of restricted stock (in shares)					29,000
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units (in shares)					(56,000)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units	(837)							(837)
Forfeitures (in shares)					(26,000)
Dividends declared	(62,275)								(62,275)
Exchange of noncontrolling interest for common stock (in shares)			4,349,832	(4,349,832)	4,350,000	(4,350,000)
Exchange of noncontrolling interest for common stock	313				$ 5	$ (5)	60,110			(143)	(59,654)
Net income (loss)	111,365								89,281		13,795	8,289
Other comprehensive income (loss)	(11,104)									(9,506)	(1,598)
Rebalancing of ownership percentage between Company and Operating Partnership							(659)			6	653
Ending Balance (in shares) at Jun. 30, 2018					97,938,000	13,318,000
Ending Balance at Jun. 30, 2018	1,512,462				$ 99	$ 13	1,370,092	(32,793)	(12,106)	(9,855)	185,158	11,854
Beginning Balance (in shares) at Mar. 31, 2018					97,956,000	13,318,000
Beginning Balance at Mar. 31, 2018	1,503,292				$ 99	$ 13	1,368,548	(32,684)	(18,659)	(7,880)	184,201	9,654
Increase Decrease in Stockholders' Equity
Contributions	2,405											2,405
Distributions	(4,698)										(4,626)	(72)
Amortization of equity based compensation	2,105						2,105
Grants of restricted stock (in shares)					4,000
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units (in shares)					(7,000)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units	(109)							(109)
Forfeitures (in shares)					(15,000)
Dividends declared	(31,853)								(31,853)
Net income (loss)	43,567								38,406		5,294	(133)
Other comprehensive income (loss)	(2,247)									(1,978)	(269)
Rebalancing of ownership percentage between Company and Operating Partnership	0						(561)			3	558
Ending Balance (in shares) at Jun. 30, 2018					97,938,000	13,318,000
Ending Balance at Jun. 30, 2018	1,512,462				$ 99	$ 13	1,370,092	(32,793)	(12,106)	(9,855)	185,158	11,854
Beginning Balance (in shares) at Dec. 31, 2018					103,941,000	13,118,000
Beginning Balance at Dec. 31, 2018	1,643,635	[1]			$ 105	$ 13	1,471,157	(32,815)	11,342	(4,649)	188,427	10,055
Increase Decrease in Stockholders' Equity
Contributions	191											191
Distributions	(8,799)										(8,537)	(262)
Amortization of equity based compensation	14,761						14,761
Grants of restricted stock (in shares)					1,478,000
Grants of restricted stock					$ 1		(1)
Purchase of treasury stock (in shares)					(40,000)
Purchase of treasury stock	(637)							(637)
Re-issuance of treasury stock (in shares)					68,000
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units (in shares)					(461,000)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units	(8,083)							(8,083)
Forfeitures (in shares)					(9,000)
Dividends declared	(72,785)								(72,785)
Stock dividends (in shares)					1,435,000
Stock dividends	0				$ 1	$ 180	23,822		(23,823)
Exchange of noncontrolling interest for common stock (in shares)					1,139,000	(1,139,000)
Exchange of noncontrolling interest for common stock	405				$ 1	$ (1)	16,449			65	(16,109)
Net income (loss)	60,604								54,419		6,939	(754)
Other comprehensive income (loss)	18,782									16,738	2,044
Rebalancing of ownership percentage between Company and Operating Partnership							281			17	(298)
Ending Balance (in shares) at Jun. 30, 2019					107,551,000	12,159,000
Ending Balance at Jun. 30, 2019	1,648,074	[1]			$ 108	$ 12	1,526,469	(41,535)	(30,847)	12,171	172,466	9,230
Beginning Balance (in shares) at Mar. 31, 2019					106,562,000	13,198,000
Beginning Balance at Mar. 31, 2019	1,644,243				$ 107	$ 13	1,508,452	(40,799)	(26,549)	7,080	186,310	9,629
Increase Decrease in Stockholders' Equity
Contributions	114											114
Distributions	(4,490)										(4,284)	(206)
Amortization of equity based compensation	3,469						3,469
Purchase of treasury stock (in shares)					(40,000)
Purchase of treasury stock	(637)							(637)
Re-issuance of treasury stock (in shares)					5,000
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units (in shares)					(6,000)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock and units	(99)							(99)
Forfeitures (in shares)					(9,000)
Dividends declared	(36,542)								(36,542)
Exchange of noncontrolling interest for common stock (in shares)					1,039,000	(1,039,000)
Exchange of noncontrolling interest for common stock	354				$ 1	$ (1)	14,956			70	(14,672)
Net income (loss)	36,073								32,244		4,136	(307)
Other comprehensive income (loss)	5,589									5,007	582
Rebalancing of ownership percentage between Company and Operating Partnership	0						(408)			14	394
Ending Balance (in shares) at Jun. 30, 2019					107,551,000	12,159,000
Ending Balance at Jun. 30, 2019	$ 1,648,074	[1]			$ 108	$ 12	$ 1,526,469	$ (41,535)	$ (30,847)	$ 12,171	$ 172,466	$ 9,230

[1] Includes amounts relating to consolidated variable interest entities. See Note 3.