Employee Incentive Plan (Share-Based Compensation Schedule) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Restricted Stock Units (RSUs) [Member]
Number of Shares
Non-vested beginning of period (Units)	1,003,159
Granted (Units)	625,339
Vested (Units)	(396,927)	[1]
Forfeited (Units)	(52,648)
Non-vested, end of period (Units)	1,178,923
Aggregate intrinsic value, end of period (in thousands)	$ 23,461
Weighted Average Grant-Date Fair Value
Non-vested beginning of period	$ 13.31
Granted	$ 16.19
Vested	$ 9.50	[1]
Forfeited	$ 13.52
Non-vested, end of period	$ 16.11
Vested units withheld for payroll taxes on behalf of employees	113,804
Restricted Stock [Member]
Number of Shares
Non-vested beginning of period (Units)	1,329,162
Granted (Units)	632,912
Vested (Units)	(445,177)
Forfeited (Units)	(63,864)
Non-vested, end of period (Units)	1,453,033
Aggregate intrinsic value, end of period (in thousands)	$ 30,354
Weighted Average Grant-Date Fair Value
Non-vested beginning of period	$ 9.75
Granted	$ 15.08
Vested	$ 7.43
Forfeited	$ 11.69
Non-vested, end of period	$ 12.69
Vested units withheld for payroll taxes on behalf of employees	124,493

[1] Vested units include 113,804 units withheld for payroll taxes paid on behalf of employees.