Equity Based Award Plans (Monte Carlo assumptions) (Details) (Restricted Stock [Member])	12 Months Ended
	Dec. 31, 2013
Risk-free interest rate, minimum	0.10%
Risk-free interest rate, maximum	0.50%
Expected life (performance period)	3 years
AERC [Member]
Expected volatility, minimum	18.10%
Expected volatility, maximum	22.50%
Peer Group [Member]
Expected volatility, minimum	14.70%
Expected volatility, maximum	29.50%