Business Information - Information by Geographic Region, After Elimination of All Significant Inter-company Accounts and Transactions (Details) (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
Segment Reporting Disclosure [Line Items]
Total revenues	$ 92,300	$ 62,700	$ 47,300	$ 82,700	$ 94,500	$ 60,400	$ 90,700	$ 48,400	$ 285,079	$ 293,993	$ 278,329
Income (loss) before taxes	28,100	13,900	3,500	24,800	25,100	13,000	33,100	(2,600)	70,475	68,670	58,951
Total assets	386,970				460,743				386,970	460,743	508,677
North America
Segment Reporting Disclosure [Line Items]
Total revenues									179,204	153,812	172,462
Income (loss) before taxes									56,837	22,812	43,276
Total assets	165,118				193,661				165,118	193,661	236,014
Europe
Segment Reporting Disclosure [Line Items]
Total revenues									57,606	60,068	53,005
Income (loss) before taxes									8,447	12,578	(7,351)
Total assets	41,251				71,965				41,251	71,965	79,322
Australia
Segment Reporting Disclosure [Line Items]
Total revenues									44,801	70,669	40,827
Income (loss) before taxes									10,982	33,776	19,352
Total assets	175,095				186,463				175,095	186,463	185,895
Asia
Segment Reporting Disclosure [Line Items]
Total revenues									3,468	9,444	12,035
Income (loss) before taxes									(5,791)	(496)	3,674
Total assets	$ 5,506				$ 8,654				$ 5,506	$ 8,654	$ 7,446