CASH AND CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Composition of cash and cash equivalents
Cash and amounts due from banks	$ 1,177,889	$ 944,118
Cash equivalents:
Interest-bearing deposits in other banks	68,000	0
Bank placements	114,998	95,767
Total cash and cash equivalents	1,360,887	1,039,885	$ 895,820	$ 1,323,106
Short-term investments
Short-term investments	299,916	338,714
Short-term Investments [Member]
Cash equivalents:
Interest-bearing deposits in other banks	$ 160,900	$ 50,200