FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Liabilities:
Senior notes	$ 412,617	$ 413,006
Junior subordinated notes	248,903	248,498
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash, restricted cash, and cash equivalents	738,423	807,496
Liabilities:
Senior notes	391,250	394,390
Junior subordinated notes	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash, restricted cash, and cash equivalents	0	0
Liabilities:
Senior notes	0	0
Junior subordinated notes	0	0
Significant Unobservable Inputs (Level 3)
Assets:
Cash, restricted cash, and cash equivalents	0	0
Liabilities:
Senior notes	0	0
Junior subordinated notes	200,179	216,757
Carrying Amount
Assets:
Cash, restricted cash, and cash equivalents	738,423	807,496
Liabilities:
Senior notes	412,617	413,006
Junior subordinated notes	248,903	248,498
Estimated Fair Value
Assets:
Cash, restricted cash, and cash equivalents	738,423	807,496
Liabilities:
Senior notes	391,250	394,390
Junior subordinated notes	$ 200,179	$ 216,757