Stockholders' Equity (Details 3) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018		Dec. 31, 2018
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	$ 14,803	$ 14,274	$ 13,841	$ 8,344		$ 51,262
Distributions Paid	14,576	14,118	13,636	11,146		$ 53,476
Common Class A [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	3,819	3,847	3,863	(79)	[1]
Distributions Paid	3,846	3,864	3,858	2,341	[1]
Common Class C [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	12	12	12	0
Distributions Paid	12	12	12	7
Series A Preferred Stock [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	2,950	2,950	2,950	2,950
Distributions Paid	2,950	2,950	2,950	2,950
Series B Preferred Stock [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	4,316	3,779	3,316	2,921
Distributions Paid	4,101	3,631	3,161	2,816
Series C Preferred Stock [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	1,107	1,107	1,107	1,107
Distributions Paid	1,107	1,107	1,107	1,107
Series D Preferred Stock [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	1,269	1,269	1,269	1,270
Distributions Paid	1,269	1,269	1,269	1,270
Operating Partnership Units [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	1,038	1,013	1,013	0
Distributions Paid	1,012	1,013	1,013	602
Long-term Incentive Plan Units [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	292	297	311	175
Distributions Paid	$ 279	$ 272	$ 266	$ 53

[1] On December 20, 2017, the Company’s Board authorized, and the Company declared, a quarterly dividend for the first quarter of 2018 equal to a quarterly rate of $0.1625 per share on the Class A and Class C common stock, payable to the stockholders of record as of March 23, 2018, which was paid in cash on April 5, 2018. Holders of OP and LTIP Units are entitled to receive “distribution equivalents” at the same time as dividends are paid to holders of the Class A common stock. The Company recorded an estimated accrued distribution at December 31, 2017 based on the Class A common stock outstanding. Due to the impact of the Class A common stock repurchase program that was initiated in February 2018, the distribution required based on the outstanding Class A common stock at the March 23, 2018 record date was lower than the accrued distribution recorded at December 31, 2017 and therefore, a negative declared distribution is reflected.