Related-Party Transactions (Details) (USD $)	3 Months Ended		6 Months Ended					0 Months Ended		0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Apr. 16, 2007	Jun. 03, 2013 Delayed Draw [Member] New Credit Agreement [Member]	Jul. 03, 2013 Delayed Draw [Member] Subsequent Event [Member] New Credit Agreement [Member] Oaktree [Member]	Jun. 03, 2013 Term Loan Facility [Member] New Credit Agreement [Member]	Jun. 30, 2013 Term Loan Facility [Member] New Credit Agreement [Member]	Jun. 03, 2013 Term Loan Facility [Member] New Credit Agreement [Member] Oaktree [Member]
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)	51.20%		51.20%		49.70%
Revenues from management agreements with unconsolidated equity investees	$ 2,276,000	$ 1,813,000	$ 4,520,000	$ 3,637,000
Amounts of the revenues and expenses	1,814,000	1,817,000	3,623,000	3,641,000
Debt amount funded							9,524,000		337,921,000	40,476,000
Term loan facility borrowing capacity						$ 80,000,000	$ 80,000,000	$ 340,000,000		$ 340,000,000
Debt term (years)								6 years		6 years