Supplemental Cash Flow Disclosures - Non-Cash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Supplemental Cash Flow Disclosures Noncash Investing And Financing Activities [Abstract]
Capital property and equipment acquired on account, but not paid as of December 31	$ 9,791	$ 10,268	$ 7,040
Retirement Savings Plan	777	690	602
Conversion of Debentures	0	0	535
Performance Incentive Plan	1,027	1,594	1,533
Capital Lease Obligation	3,471	4,824	6,130
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 0	$ 30,164	$ 0