Related-Party Transactions (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended							0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Apr. 16, 2007	Jun. 03, 2013 New Credit Agreement Term Loan Facility	Sep. 30, 2014 New Credit Agreement Term Loan Facility	Jul. 03, 2013 New Credit Agreement Term Loan Facility	Jun. 03, 2013 New Credit Agreement Delayed Draw	Dec. 02, 2013 New Credit Agreement Committed Incremental Term Loan	Nov. 07, 2013 New Credit Agreement Committed Incremental Term Loan	Oct. 11, 2013 New Credit Agreement Committed Incremental Term Loan	Jun. 03, 2013 Oaktree [Member] New Credit Agreement Term Loan Facility	Jul. 03, 2013 Oaktree [Member] New Credit Agreement Delayed Draw	Nov. 07, 2013 Oaktree [Member] New Credit Agreement Committed Incremental Term Loan
Related Party Transaction [Line Items]
Shares purchased by Oaktree and MTS (shares)					4,900,301
Percentage of outstanding stock owned by Oaktree and MTS (percent)	50.70%		50.70%		49.70%
Revenues from management agreements with unconsolidated equity investees	$ 2,235,000	$ 2,756,000	$ 6,797,000	$ 7,276,000
Amounts of the revenues and expenses	1,764,000	2,291,000	5,451,000	5,914,000
Debt amount funded							484,050,000			70,000,000			40,476,000	9,524,000
Term loan facility borrowing capacity						$ 340,000,000		$ 340,000,000	$ 80,000,000	$ 70,000,000	$ 70,000,000	$ 70,000,000	$ 340,000,000	$ 80,000,000	$ 10,000,000
Debt term (years)						6 years							6 years