Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements [Table Text Block]

			Fair Value Measurement at
			June 30, 2017
	Total		Level 1		Level 2		Level 3
Assets:
Deferred compensation trust assets (1)	$	26,788	$	—	$	26,788	$	—
Liabilities:
Deferred compensation plan	$	33,963	$	—	$	33,963	$	—
5 year interest rate swap	103		—		103		—
10 year interest rate swap	833		—		833		—
	$	34,899	$	—	$	34,899	$	—

			Fair Value Measurement at
			December 31, 2016
	Total		Level 1		Level 2		Level 3
Assets:
Deferred compensation trust assets (1)	$	25,530	$	—	$	25,530	$	—
Liabilities:
Deferred compensation plan	$	31,672	$	—	$	31,672	$	—
5 year interest rate swap	211		—		211		—
10 year interest rate swap	835		—		835		—
	$	32,718	$	—	$	32,718	$	—
(1) Trust assets consist of the cash surrender value of life insurance policies and are intended to assist in the funding of the deferred compensation agreements.