Earnings per Share (Summary of Basic and Diluted Earnings per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings per Share [Abstract]
Net income available to common stockholders		$ 4,632	$ 3,090	$ 8,714	$ 7,288
Weighted average shares outstanding-basic		36,668,755	29,016,774	33,996,467	29,001,374
Net income per share-basic		$ 0.13	$ 0.11	$ 0.26	$ 0.25
Net income		$ 5,520	$ 3,921	$ 10,557	$ 9,249
Weighted average shares outstanding-diluted	[1]	44,444,104	37,009,746	41,867,944	36,934,210
Net income per share-diluted		$ 0.12	$ 0.11	$ 0.25	$ 0.25

[1] Includes 7,063 Class A and Class RS units, 492 "in the money" value of Class O units on an "as if" converted basis and 220 "in the money" value of options to purchase shares of Class A common stock on an "as if" converted basis as of the three months ended June 30, 2015, and 7,189 Class A and Class RS units, 464 "in the money" value of Class O units on an "as if" converted basis and 218 "in the money" value of options to purchase shares of Class A common stock on an "as if" converted basis as of the six months ended June 30, 2015. As of the three months ended June 30, 2014, this amount included 7,797 Class A and Class RS units, 89 "in the money" value of Class O units on as "as if" converted basis and 107 "in the money" value options to purchase shares of Class A common stock on an "as if" converted basis, and as of the six months ended June 30, 2014, this amount included 7,797 Class A and Class RS units, 57 "in the money" value of Class O units on an "as if" converted basis and 79 "in the money" value options to purchase shares of Class A common stock on as "as if" converted basis.