Equity (High Performance Unit Program) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
HPU
Stock Performance Award Program [Line Items]
Number of votes per share	0.25
High Performance Unit Program
Stock Performance Award Program [Line Items]
Initial purchase price of high performance units	$ 9.8
Number of plans which did not meet the required performance thresholds	4
High Performance Unit Program | Employee
Stock Performance Award Program [Line Items]
Number of plans which have exceeded performance thresholds	3
High Performance Unit Program 2002 Plan | Employee | HPU
Stock Performance Award Program [Line Items]
Number of shares of entity's common stock used as the basis for determining amount of distributions to be paid	819,254
Number of shares outstanding (in shares)	5,000
High Performance Unit Program 2003 Plan | Employee | HPU
Stock Performance Award Program [Line Items]
Number of shares of entity's common stock used as the basis for determining amount of distributions to be paid	987,149
Number of shares outstanding (in shares)	5,000
High Performance Unit Program 2004 Plan | Employee | HPU
Stock Performance Award Program [Line Items]
Number of shares of entity's common stock used as the basis for determining amount of distributions to be paid	1,031,875
Number of shares outstanding (in shares)	5,000