Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Equity allocation between controlling and non-controlling interests
Balance	$ 632,438
Net income	17,004	12,976
Vested stock option and restricted common stock	666	985
Stock option exercise	238
Reclassification adjustment	(9)	(9)
Preferred stock dividends	(818)	(818)
Common stock dividends	(17,742)
Other	(7)
Balance	$ 631,770