INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reconciliation of income tax expense reported to amount computed by applying the U.S. federal tax rate
Provision for income taxes at the statutory rate of 35%	$ 10,900	$ 18,178	$ 41,677	$ 52,885
Tax-exempt interest income	(1,020)	(1,082)	(3,149)	(3,098)
Dividends received deduction	(626)	(603)	(1,676)	(1,715)
ESOP dividends paid deduction	(238)	(234)	(714)	(693)
Other items, net	(137)	(230)	205	30
Total tax expense	$ 8,879	$ 16,029	$ 36,343	$ 47,409
Reconciliation of income tax expense rate to the U.S. federal tax rate
U.S. federal tax rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Effective rate reduction due to tax exempt interest income (as a percent)	(3.20%)	(2.10%)	(2.60%)	(2.00%)
Effective rate reduction due to dividend received (as a percent)	(2.00%)	(1.20%)	(1.40%)	(1.10%)
Effective rate reduction due to dividend paid to ESOP (as a percent)	(0.80%)	(0.40%)	(0.60%)	(0.50%)
Effective rate reduction due to other items, net (as a percent)	(0.50%)	(0.40%)	0.10%	(0.00%)
Effective tax rates (as a percent)	28.50%	30.90%	30.50%	31.40%