Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Dec. 31, 2015

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value Measurements, Nonrecurring [Table Text Block]

	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	$	—

	Fair Value Measurement at December 31, 2015
	Total		Level 1		Level 2		Level 3
Assets:
Deferred compensation trust assets (1)	$	23,737	$	—	$	23,737	$	—
Liabilities:
Deferred compensation plan	$	29,155	$	—	$	29,155	$	—
5 year interest rate swap	353		—		353		—
10 year interest rate swap	1,229		—		1,229		—
	$	30,737	$	—	$	30,737	$	—
(1) Trust assets consist of the cash surrender value of life insurance policies and are intended to fund the deferred compensation agreements.