INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
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%	$ 18,178	$ 17,008	$ 52,885	$ 50,053
Tax-exempt interest income	(1,082)	(1,033)	(3,098)	(3,115)
Dividends received deduction	(603)	(633)	(1,715)	(1,764)
ESOP dividends paid deduction	(234)	(218)	(693)	(639)
Other items, net	(230)	216	30	525
Total tax expense	$ 16,029	$ 15,340	$ 47,409	$ 45,060
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)	(2.10%)	(2.10%)	(2.00%)	(2.20%)
Effective rate reduction due to dividend received (as a percent)	(1.20%)	(1.30%)	(1.10%)	(1.20%)
Effective rate reduction due to dividend paid to ESOP (as a percent)	(0.40%)	(0.40%)	(0.50%)	(0.50%)
Effective rate reduction due to other items, net (as a percent)	(0.40%)	0.40%	(0.00%)	0.40%
Effective tax rates (as a percent)	30.90%	31.60%	31.40%	31.50%