Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Schedule of multiemployer plans

The following table presents the Company's participation in these plans:

	Pension Plan	Pension Protection Act ("PPA")		FIP/RP								Expiration
Pension Trust	Employer	Certified Zone Status (1)		Status	Contributions						Surcharge	of Collective
Fund	Identification Number	2016	2015	P/I (2)	2016		2015		2014		Imposed	Bargaining Agreement
International Union of Operating Engineers - Employers Construction Industry Retirement Plan - Local 302 and 612 Trust Funds	91-6028571	Green	Green	N/A	$	2,158	$	1,518	$	1,295	—	2018
Associated General Contractors of Washington Carpenter, Piledrivers, and Millwrights	91-6029051 91-6029049	Green	Green	N/A	$	938	$	748	$	737	—	2018
Alaska Carpenters Trust Fund	92-0120866	Green	Green	N/A	$	889	$	807	$	1,044	—	2017
Alaska Laborers Trust Fund	91-6028298	Yellow	Orange	P	$	126	$	110	$	246	—	2017

1.    The most recent PPA zone status available in 2016 and 2015 is for the plan's year end during 2015 and 2014, respectively. Zone status is based on information received from the plan and is indicative of the plans funding status. Among other factors, plans in the red zone are generally less than 65 percent funded, plans in the orange zone are less than 80 percent funded and have an Accumulated Funding Deficiency in the current year or projected into the next six years, plans in the yellow zone are less than 80 percent funded, and plans in the green zone are at least 80 percent funded.

2.    The FIP/RP Status P/I column indicates plans for which a financial improvement plan ("FIP") or a rehabilitation plan ("RP") is either pending ("P"), or implemented ("I").