Revenue

3 Months Ended

Mar. 31, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of revenue

The following table shows net sales classified by major product category for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
(in thousands)	2020		2019
Millwork, doors & windows	$	295,669	$	239,922
Structural components	160,344		141,276
Lumber & lumber sheet goods	259,139		241,959
Other building products & services	205,727		202,248
Total net sales	$	920,879	$	825,405

The following table reflects the Company’s estimate of net sales by each customer type for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
(in thousands)	2020		2019
Single-family homebuilders	$	674,771	$	628,718
Remodeling contractors	104,669		88,208
Multi-family, commercial & other contractors	141,439		108,479
Total net sales	$	920,879	$	825,405

Net sales for the Company's building products contracts was $686.7 million and $620.9 million for the three months ended March 31, 2020 and 2019, respectively. Net sales for the Company's construction services contracts, which includes both products and installation services, was $234.2 million and $204.5 million for the three months ended March 31, 2020 and 2019, respectively.

Contract balances

The following table reflects the Company’s contract balances as of March 31, 2020 and December 31, 2019:



(in thousands)	March 31, 2020		December 31, 2019		Change
Receivables, including unbilled receivables presented in prepaid expenses and other current assets	$	364,398	$	333,044	$	31,354
Contract assets	38,339		32,125		6,214
Contract liabilities	$	37,859	$	31,094	$	6,765

During the three months ended March 31, 2020, the Company’s contract assets increased by $6.2 million and the Company’s contract liabilities increased by $6.8 million. The changes in contract assets and liabilities were primarily due to the timing of revenue recognition, as the balances were not materially impacted by any other factors. For the three months ended March 31, 2020, the Company recognized revenue of $24.4 million that was included in contract liabilities as of December 31, 2019. Revenue recognized related to performance obligations that were satisfied or partially satisfied in previous periods was not material for the three months ended March 31, 2020.

As permitted by ASC 606, Revenue from Contracts with Customers, the Company has elected not to disclose the value of unsatisfied performance obligations, as the Company’s contracts generally have an original expected length of one year or less.