Stockholders' Equity (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	$ 4,006
Distributions Paid	3,560
Common Class A [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	3,554
Distributions Paid	3,073
Common Class B-1 One [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	68
Distributions Paid	103
Common Class B-2 One [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	103
Distributions Paid	103
Common Class B-3 One [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	103
Distributions Paid	103
Operating Partnership Units [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	82
Distributions Paid	82
Long-term Incentive Plan Units [Member]
Distribution Made to Unit-holder Of Limited Partnership [Line Items]
Distributions Declared	96
Distributions Paid	$ 96