Earnings per Share (Summary of Basic and Diluted Earnings per Share Footnote) (Details) - shares		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares outstanding-diluted	[1]	44,444,104	37,009,746	41,867,944	36,934,210
Class A Units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares outstanding-diluted		7,063,000	7,797,000	7,189,000	7,797,000
Class O Units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares outstanding-diluted		492,000	89,000	464,000	57,000
Class RS Units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares outstanding-diluted		7,063,000	7,797,000	7,189,000	7,797,000
Options to purchase Class A common stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares outstanding-diluted		220,000	107,000	218,000	79,000

[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.