SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Surety	Dec. 31, 2010 Surety	Apr. 30, 2011 Contractors Bonding and Insurance Company (CBIC)
ADOPTED ACCOUNTING STANDARDS
Maximum carrying amount of reporting unit for goodwill impairment testing	$ 0		$ 0
Goodwill
Goodwill and intangibles	56,475		56,475		26,214	26,200	26,200	30,300
Basic EPS, Income (Numerator)
Income available to common shareholders	47,381	34,994	73,842	59,215
Diluted EPS, Income (Numerator)
Income available to common shareholders	$ 47,381	$ 34,994	$ 73,842	$ 59,215
Basic EPS, Shares (Denominator)
Number of shares outstanding (in shares)	21,075	21,026	21,050	21,100
Effect of Dilutive Securities, Shares (Denominator)
Stock options (in shares)	257	197	265	198
Diluted EPS, Shares (Denominator)
Number of shares outstanding (in shares)	21,332	21,223	21,315	21,298
Basic EPS, Per Share Amount
Basic earnings per share (in dollars per share)	$ 2.25	$ 1.66	$ 3.51	$ 2.81
Diluted EPS, Per Share Amount
Diluted earnings per share (in dollars per share)	$ 2.22	$ 1.65	$ 3.46	$ 2.78