Statement of Cash Flows - Noncash Investing and Financing Activities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Line Items]
Noncash investing activities, payables incurred for property, plant and equipment expenditures, unpaid	$ 16,890,000	$ 15,119,000	$ 12,600,000
Common Stock [Member] | Stock Award Plan [Member]
Supplemental Cash Flow Elements [Line Items]
Noncash financing activities shares issued	96,095	99,497	35,372
Noncash financing activities issued value	$ 8,893,000	$ 7,931,000	$ 2,941,000