Fair Value Measurements (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) Investment	Dec. 31, 2014 USD ($)
Financial Liabilities [Abstract]
Corporate bond investments | Investment	6
Investments included in Level 1 were transferred to Level 2	$ 1,141
Net unrealized losses incurred	(144)	$ (17)
Measured at Fair Value on a Recurring Basis [Member]
Financial Assets [Abstract]
Derivative financial instruments	2,068	547
Total financial assets	15,716	13,856
Financial Liabilities [Abstract]
SERP liabilities	5,560	8,128
Derivative financial instruments	25
Total financial liabilities	5,585	8,128
Measured at Fair Value on a Recurring Basis [Member] | SERP Money Market Fund [Member]
Financial Assets [Abstract]
Investments	691	532
Measured at Fair Value on a Recurring Basis [Member] | SERP Mutual Funds [Member]
Financial Assets [Abstract]
Investments	2,726	3,195
Measured at Fair Value on a Recurring Basis [Member] | Preferred Stocks [Member]
Financial Assets [Abstract]
Investments	743	973
Measured at Fair Value on a Recurring Basis [Member] | Corporate Bonds [Member]
Financial Assets [Abstract]
Investments	5,031	4,009
Measured at Fair Value on a Recurring Basis [Member] | Municipal Bonds [Member]
Financial Assets [Abstract]
Investments	1,593	2,060
Measured at Fair Value on a Recurring Basis [Member] | Floating Rate Notes [Member]
Financial Assets [Abstract]
Investments	307	422
Measured at Fair Value on a Recurring Basis [Member] | US Treasury Bills [Member]
Financial Assets [Abstract]
Investments		622
Measured at Fair Value on a Recurring Basis [Member] | Asset Backed Securities [Member]
Financial Assets [Abstract]
Investments	860
Measured at Fair Value on a Recurring Basis [Member] | Other [Member]
Financial Assets [Abstract]
Investments	1,697	1,496
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member]
Financial Assets [Abstract]
Derivative financial instruments	0	0
Total financial assets	6,447	8,247
Financial Liabilities [Abstract]
SERP liabilities	0	0
Derivative financial instruments	0
Total financial liabilities	0	0
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | SERP Money Market Fund [Member]
Financial Assets [Abstract]
Investments	691	532
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | SERP Mutual Funds [Member]
Financial Assets [Abstract]
Investments	2,726	3,195
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | Preferred Stocks [Member]
Financial Assets [Abstract]
Investments	743	973
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | Corporate Bonds [Member]
Financial Assets [Abstract]
Investments	2,212	2,825
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | Municipal Bonds [Member]
Financial Assets [Abstract]
Investments	0	0
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | Floating Rate Notes [Member]
Financial Assets [Abstract]
Investments	0	100
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | US Treasury Bills [Member]
Financial Assets [Abstract]
Investments		622
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | Asset Backed Securities [Member]
Financial Assets [Abstract]
Investments	0
Measured at Fair Value on a Recurring Basis [Member] | Level 1 [Member] | Other [Member]
Financial Assets [Abstract]
Investments	75	0
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member]
Financial Assets [Abstract]
Derivative financial instruments	2,068	547
Total financial assets	9,269	5,609
Financial Liabilities [Abstract]
SERP liabilities	5,560	8,128
Derivative financial instruments	25
Total financial liabilities	5,585	8,128
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | SERP Money Market Fund [Member]
Financial Assets [Abstract]
Investments	0	0
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | SERP Mutual Funds [Member]
Financial Assets [Abstract]
Investments	0	0
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | Preferred Stocks [Member]
Financial Assets [Abstract]
Investments	0	0
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | Corporate Bonds [Member]
Financial Assets [Abstract]
Investments	2,819	1,184
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | Municipal Bonds [Member]
Financial Assets [Abstract]
Investments	1,593	2,060
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | Floating Rate Notes [Member]
Financial Assets [Abstract]
Investments	307	322
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | US Treasury Bills [Member]
Financial Assets [Abstract]
Investments		0
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | Asset Backed Securities [Member]
Financial Assets [Abstract]
Investments	860
Measured at Fair Value on a Recurring Basis [Member] | Level 2 [Member] | Other [Member]
Financial Assets [Abstract]
Investments	$ 1,622	$ 1,496