Shareholders' Equity and Stock Options (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2011
Summary of changes in outstanding restricted common stock units
Beginning balance, Total Outstanding, Units	1,423,611		1,135,840
Granted, Total Outstanding Units	484,552	[1]
Vested, Total Outstanding Units	0
Forfeited, Total Outstanding Units	(24,507)
Distributed, Total Outstanding Units	(220,466)	[2]
Ending balance, Total Outstanding, Units	1,663,190		1,135,840
Beginning balance, Total Outstanding, Weighted Average Grant Date Fair Value per Unit	$ 15.93
Grant, Total Outstanding, Weighted Average Grant Date Fair Value per Unit	$ 25.13	[1]
Vested, Total Outstanding, Weighted Average Grant Date Fair Value per Unit	$ 0
Forfeited, Total Outstanding, Weighted Average Grant Date Fair Value per Unit	$ 15.62
Distributed, Total Outstanding, Weighted Average Grant Date Fair Value per Unit	$ 9.87	[2]
Ending balance, Total Outstanding, Weighted Average Grant Date Fair Value per Unit	$ 19.41
Beginning balance, Vested, Units	311,407
Vested Units	282,680
Granted, Vested, Units	0	[1]
Distributed, Vested, Units	(220,466)	[2]
Forfeited, Vested, Units	0
Ending balance, Vested, Units	373,621
Beginning balance, Vested, Weighted Average Grant Date Fair Value per Unit	$ 13.15
Granted, Weighted Average Grant Date Fair Value per Unit	$ 0	[1]
Vested, Weighted Average Grant Date Fair Value per Unit	$ 13.50
Forfeited, Weighted Average Grant Date Fair Value per Unit	$ 0
Distributed, Vested, Weighted Average Grant Date Fair Value per Unit	$ 9.87	[2]
Ending balance, Vested, Weighted Average Grant Date Fair Value per Unit	$ 15.34

[1] Includes dividends reinvested into additional restricted common stock units.

[2] Includes distributed units which were utilized to satisfy withholding taxes due on the distribution.