Stock-Based Awards and Programs (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended		9 Months Ended											12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Employee Stock Purchase Plan	Sep. 30, 2011 Employee Stock Purchase Plan	Sep. 30, 2012 Performance-Based Restricted Stock Awards	Sep. 30, 2011 Performance-Based Restricted Stock Awards	Sep. 30, 2012 Performance-Based Restricted Stock Awards Minimum	Sep. 30, 2011 Performance-Based Restricted Stock Awards Minimum	Sep. 30, 2012 Performance-Based Restricted Stock Awards Maximum	Sep. 30, 2011 Performance-Based Restricted Stock Awards Maximum	Sep. 30, 2012 Stock Options	Sep. 30, 2011 Stock Options	Sep. 30, 2012 Time-Vested Restricted Stock Awards	Dec. 31, 2011 Time-Vested Restricted Stock Awards
Stock-Based Awards and Programs
Compensation Expense	$ 431,000	$ 358,000	$ 1,629,000	$ 1,317,000	$ 2,077,000	$ 2,414,000
Tax Benefit Recognized	148,000	121,000	575,000	460,000	730,000	866,000
Assumptions used in the model for each grant year
Risk-free interest rate, low end of range (as a percent)									0.13%	0.02%					0.15%	0.13%
Risk-free interest rate, high end of range (as a percent)									0.25%	0.29%					0.41%	0.94%
Expected volatility (as a percent)							24.00%	22.00%	20.50%	27.80%					25.00%	24.00%
Expected volatility of peer group stock (as a percent)											12.40%	20.40%	45.60%	78.00%
Expected dividend yield on Empire stock (as a percent)							5.00%	2.60%	4.60%	4.60%					4.60%
Expected forfeiture rates (as a percent)									3.00%	3.00%
Plan cycle									3 years	3 years
Fair value percentage											33.00%	62.00%	106.00%	87.00%
Expected life							12 months	12 months							78 months	78 months
Weighted average fair value per share (in dollars per share)									$ 13.25	$ 14.85
Expected dividend yield, low end of range (as a percent)																4.10%
Expected dividend yield, high end of range (as a percent)																4.90%
Market value (in dollars per share)															$ 21.55	$ 19.38
Weighted average fair value per option (in dollars per share)															$ 1.94	$ 1.42
Risk-free interest rate (as a percent)							0.17%	0.18%
Changes in restricted stock awards
Nonvested, balance at the beginning of the period (in shares)									37,400	47,500							3,433
Granted (in shares)									10,000	10,900								10,200
Awarded in excess of target (in shares)										18,621
Awarded/Vested (in shares)									(7,823)	(39,621)								(794)
Not Awarded (in shares)									(5,677)
Distributed (in shares)																	(133)	(661)
Forfeited (in shares)																		(6,106)
Vested but not distributed (in shares)																		133
Nonvested, balance at the end of the period (in shares)							71,438	72,182	33,900	37,400							3,300	3,433
Weighted Average Grant Date Price
Nonvested, balance at the beginning of the period (in dollars per share)									$ 19.28	$ 19.86							$ 21.84
Granted (in dollars per share)									$ 20.97	$ 21.84								$ 21.84
Awarded in Excess of target (in dollars per share)										$ 21.92
Awarded/Vested (in dollars per share)									$ 18.12	$ 21.92								$ 19.32
Not Awarded (in dollars per share)									$ 18.12
Distributed (in dollars per share)																	$ 20.13	$ 21.02
Vested but not distributed (in dollars per share)																		$ 20.13
Granted (in dollars per share)							$ 3.19	$ 3.17
Nonvested, balance at the end of the period (in dollars per share)									$ 20.25	$ 19.28							$ 20.35	$ 21.84
Unrecognized compensation cost related to estimated outstanding awards									$ 200,000
Period from date of termination of employment due to death, retirement or disability during which the pro-rata portion of the awards are distributed																		6 months
Vesting period																		3 years