Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings from continuing operations	$ 60,438	$ 65,780	$ 59,066
Loss from discontinued operations, net of taxes	0	(2,924)	(2,386)
Gain (loss) on disposal of discontinued operations, net of taxes	0	(4,984)	420
Net earnings	$ 60,438	$ 57,872	$ 57,100
Basic:
Weighted average number of shares outstanding	27,177,000	27,053,000	26,744,000
Basic earnings per share from continuing operations	$ 2.22	$ 2.43	$ 2.21
Basic loss per share from discontinued operations	0.00	(0.11)	(0.09)
Basic earnings (loss) per share from disposal of discontinued operations	0.00	(0.18)	0.02
Basic earnings per share	$ 2.22	$ 2.14	$ 2.14
Diluted:
Weighted average shares issuable on exercise of dilutive stock options	133,000	147,000	159,000
Weighted average shares issuable on exercise of convertible notes	558,000	577,000	240,000
Weighted average number of shares outstanding, diluted	27,868,000	27,777,000	27,143,000
Diluted earnings per share from continuing operations	$ 2.17	$ 2.37	$ 2.17
Diluted loss per share from discontinued operations	0.00	(0.11)	(0.09)
Diluted earnings (loss) per share from disposal of discontinued operations	0.00	(0.18)	0.02
Diluted earnings per share	$ 2.17	$ 2.08	$ 2.10
Equity awards granted to employees [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	487,071	342,994	391,717
Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,422,477	3,411,539	3,404,626