Fair value measurement (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Financial Instruments Measured at Fair Value

The following table summarizes our assets measured at fair value in the accompanying Consolidated Balance Sheets as of December 31, 2016 (in thousands):

Fair value measurement as of Dec. 31, 2016 (recast)
	Level 1		Level 2		Level 3		Total
Available for sale investment	$	16,744	$	—	$	—	$	16,744
Fixed income mutual fund	13,575		—		—		13,575
Total	$	30,319	$	—	$	—	$	30,319

Fair Value of Pension Plan Assets by Level within Fair Value Hierarchy

Pension Plan Assets
Fair value measurement as of Dec. 31, 2017
	Level 1		Level 2		Level 3		Total
Assets:
Cash and other	$	935	$	—	$	—	$	935
Corporate stock	82,698		—		—		82,698
Interest in registered investment companies	45,186		—		—		45,186
Total	$	128,819	$	—	$	—	$	128,819
Pension plan investments valued using net asset value as a practical expedient:
Common collective trust - equities							$	117,778
Common collective trust - fixed income							170,977
Hedge funds							15,756
Partnership/joint venture interests							5,819
Total fair value of plan assets							$	439,149

Fair value measurement as of Dec. 31, 2016
	Level 1		Level 2		Level 3		Total
Assets:
Cash and other	$	2,206	$	—	$	—	$	2,206
Corporate stock	60,730		—		—		60,730
Interest in registered investment companies	6,803		—		—		$	6,803
Total	$	69,739	$	—	$	—	$	69,739
Pension plan investments valued using net asset value as a practical expedient:
Common collective trust - equities							$	167,647
Common collective trust - fixed income							127,043
Hedge funds							14,754
Partnership/joint venture interests							8,985
Total fair value of plan assets							$	388,168