MORTGAGE LOANS (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Mortgage loans
Mortgage loans holdings	$ 5,728,237
Amount that would become due in remainder of 2015, if loans are called at their next call dates	27,300
Amount that would become due in 2016 through 2020, if loans are called at their next call dates	944,400
Amount that would become due in 2021 through 2025, if loans are called at their next call dates	365,300
Amount that would become due after 2025, if loans are called at their next call dates	$ 114,500
Minimum
Mortgage loans
Period for exercise of call options or interest rate reset options	3 years
Maximum
Mortgage loans
Period for exercise of call options or interest rate reset options	10 years