Geographic Information for Long-Lived Assets and Revenues in United States and other Countries (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Long-lived assets:
Long-lived assets	$ 579,161				$ 489,403				$ 579,161	$ 489,403	$ 440,069
Revenues:
Revenues	167,798	155,402	176,561	148,564	164,520	201,477	153,744	147,657	648,325	667,398	645,536
UNITED STATES
Long-lived assets:
Long-lived assets	561,109				454,031				561,109	454,031	403,534
Revenues:
Revenues									491,004	529,603	500,106
CANADA
Revenues:
Revenues									73,092	43,329	30,929
Other International
Revenues:
Revenues									84,229	94,466	114,501
International, Primarily China and Russia
Long-lived assets:
Long-lived assets	$ 18,052				$ 35,372				$ 18,052	$ 35,372	$ 36,535