BUSINESS COMBINATIONS (Assets Acquired and Liabilities Assumed) (Details) (Mercer Insurance Group [Member], USD $) In Thousands, unless otherwise specified	Mar. 28, 2011
Assets
Short-term investments	$ 400
Cash and cash equivalents	18,855
Accrued investment income	3,741
Premiums receivable	35,822
Value of business acquired	27,436
Property and equipment	14,985
Reinsurance receivables and recoverables	58,193
Prepaid reinsurance premiums	6,289
Income taxes receivable	2,657
Deferred income taxes	2,837
Goodwill and intangible assets	32,293
Other assets	11,353
Total assets	626,675
Liabilities
Reserves for losses, claims and loss settlement expenses	310,647
Unearned premiums	72,249
Accrued expenses and other liabilities	33,690
Debt	3,000
Trust preferred securities	15,614
Total liabilities	435,200
Total net assets acquired	191,475
Available-for-sale Securities [Member] | Fixed Maturities [Member]
Assets
Debt and equity securities	401,548
Equity Securities [Member]
Assets
Debt and equity securities	$ 10,266