Subsequent Events (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		0 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Apr. 17, 2013 Dividend Paid [Member] Subsequent Event [Member]	Apr. 04, 2013 Time-Based Restricted Stock Units (RSUs) [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Modification in Period				61,327
Aggregate dividends, distributions, and dividend equivalents paid to common stockholders and common unitholders	$ 26,956	$ 21,191	$ 27,400