Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net sales and long-lived assets by geographical area
Net sales	$ 144,686	$ 172,113	$ 181,703	$ 158,734	$ 130,732	$ 162,366	$ 177,812	$ 132,536	$ 657,236	$ 603,446	$ 555,487
Long-Lived Assets	216,662				205,179				216,662	205,179	194,199
Wood Construction
Net sales and long-lived assets by geographical area
Net sales									558,113	536,131	496,240
Concrete Construction
Net sales and long-lived assets by geographical area
Net sales									97,967	66,031	56,591
Other
Net sales and long-lived assets by geographical area
Net sales									1,156	1,284	2,656
Largest customer | Net sales
Net sales and long-lived assets by geographical area
Percentage of net sales attributable to largest customer									10.00%	10.00%	11.00%
United States
Net sales and long-lived assets by geographical area
Net sales									479,390	433,242	401,675
Long-Lived Assets	152,456				165,636				152,456	165,636	154,182
Canada
Net sales and long-lived assets by geographical area
Net sales									44,359	42,350	43,165
Long-Lived Assets	6,182				5,964				6,182	5,964	6,117
Denmark
Net sales and long-lived assets by geographical area
Net sales									15,096	17,158	15,775
Long-Lived Assets	2,252				2,607				2,252	2,607	3,328
United Kingdom
Net sales and long-lived assets by geographical area
Net sales									23,504	23,598	20,233
Long-Lived Assets	1,232				1,370				1,232	1,370	1,660
France
Net sales and long-lived assets by geographical area
Net sales									37,826	43,319	34,552
Long-Lived Assets	10,036				10,530				10,036	10,530	12,573
Germany
Net sales and long-lived assets by geographical area
Net sales									27,919	27,237	24,221
Long-Lived Assets	17,651				4,957				17,651	4,957	1,278
Switzerland
Net sales and long-lived assets by geographical area
Net sales									6,653
Long-Lived Assets	11,628								11,628
Poland
Net sales and long-lived assets by geographical area
Net sales									4,847	3,004	2,848
Long-Lived Assets	795				224				795	224	205
The Netherlands
Net sales and long-lived assets by geographical area
Net sales									3,336
Long-Lived Assets	92								92
Portugal
Net sales and long-lived assets by geographical area
Net sales									1,437
Long-Lived Assets	734								734
Ireland
Net sales and long-lived assets by geographical area
Net sales									791	2,720	2,769
Long-Lived Assets	2,757				3,075				2,757	3,075	3,454
China/Hong Kong
Net sales and long-lived assets by geographical area
Net sales									6,054	4,754	5,027
Long-Lived Assets	9,675				10,022				9,675	10,022	10,522
Australia
Net sales and long-lived assets by geographical area
Net sales									3,386	4,586	4,205
Long-Lived Assets	441				369				441	369	276
New Zealand
Net sales and long-lived assets by geographical area
Net sales									1,404	188
Long-Lived Assets	154				138				154	138
Other countries
Net sales and long-lived assets by geographical area
Net sales									1,234	1,290	1,017
Long-Lived Assets	$ 577				$ 560				$ 577	$ 560	$ 604