Stock-based Compensation Expense Restricted and Performance Stock Unit activity (Tables)

12 Months Ended

Dec. 31, 2013

Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures [Abstract]

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

Restricted stock unit activity is summarized in the following table:

	Units		Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2010	465,428		$	17.88
Granted	152,657		23.84
Forfeited	(106,979	)	22.35
Vested	(19,702	)	23.34
Outstanding as of December 31, 2011	491,404		18.54
Granted	186,495		24.72
Forfeited	(22,947	)	18.95
Vested	(214,390	)	15.67
Outstanding as of December 31, 2012	440,562		22.54
Granted	183,071		29.25
Forfeited	(7,007	)	27.15
Vested	(185,536	)	20.20
Outstanding as of December 31, 2013	431,090		26.31

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The assumptions used in the Monte Carlo model are summarized as follows:

	2013
Stock price at March 5, 2013				$	30.29
Risk-free rate				0.34		%
Expected term (in years)				3
Expected volatility				16.77		%
Range of expected volatility for EEI Index	12.06	%	-	25.13		%
Dividend yield				0		%