Compensation and Benefit Plans (Performance Shares) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Performance Shares
Compensation and Retirement Disclosure [Abstract]
Historical period used in calculating the expected volatility (in months)			36 months
Performance Shares, Weighted-Average Grant-Date Fair Value
Vesting, market condition, performance period (in years)	3 years
Unrecognized compensation cost	$ 1.0
Performance Shares, Equity Awards
Performance Shares
Nonvested, at the beginning of the period (in shares)	41,229
Granted (in shares)	0
Forfeited (in shares)	(538)	[1]
Vested (shares)	(24,293)	[1]
Transferred to affiliates (in shares)	(460)
Nonvested, at the end of the period (in shares)	15,938		41,229
Performance Shares, Weighted-Average Grant-Date Fair Value
Nonvested, at the beginning of the period (in dollars per share)	$ 39.14
Granted (in dollars per share)	$ 0.00	[2]	$ 51.41	[2]	$ 31.14	[2]
Forfeited (in dollars per share)	$ 40.39	[1]
Vested (in dollars per share)	$ 31.04	[1]
Transferred to affiliates (in dollars per share)	$ 39.67
Nonvested, at the end of the period (in dollars per share)	$ 51.41		$ 39.14
Performance Shares, Liability Awards
Performance Shares
Nonvested, at the beginning of the period (in shares)	41,161
Granted (in shares)	0
Forfeited (in shares)	(535)	[1]
Vested (shares)	(24,271)	[1]
Transferred to affiliates (in shares)	(460)
Nonvested, at the end of the period (in shares)	15,895
Performance Shares, Weighted-Average Grant-Date Fair Value
Nonvested, at the beginning of the period (in dollars per share)	$ 46.48
Nonvested, at the end of the period (in dollars per share)	$ 57.74

[1] Includes performance shares issued in 2011 that will be paid in 2014 as the performance targets were met.

[2] The performance shares awarded in 2011 will be paid during 2014 as performance targets were met.