SHAREHOLDERS' EQUITY - AOCI Changes (Details) - USD ($) $ in Thousands		3 Months Ended
	Oct. 01, 2018	Dec. 31, 2018
Rollforward of accumulated other comprehensive income (loss), net of tax
Balance at beginning of period	$ 4,382,735	$ 4,382,735
Balance at end of period		4,326,238
ASU 2016-01 | Adjustments
Rollforward of accumulated other comprehensive income (loss), net of tax
Adoption of ASU No. 2016-01 (1)	29,100
Unrealized appreciation on securities | As Reported
Rollforward of accumulated other comprehensive income (loss), net of tax
Balance at beginning of period	29,071	29,071
Unrealized appreciation on securities | ASU 2016-01 | Adjustments
Rollforward of accumulated other comprehensive income (loss), net of tax
Adoption of ASU No. 2016-01 (1)	(29,071)
Defined Benefit Pension Plan
Rollforward of accumulated other comprehensive income (loss), net of tax
Amounts reclassified from accumulated other comprehensive income		225
Net current-period other comprehensive income		225
Balance at end of period	(12,521)	(12,296)
Defined Benefit Pension Plan | As Reported
Rollforward of accumulated other comprehensive income (loss), net of tax
Balance at beginning of period	(12,521)	(12,521)
Accumulated Other Comprehensive Income
Rollforward of accumulated other comprehensive income (loss), net of tax
Balance at beginning of period	16,550	16,550
Amounts reclassified from accumulated other comprehensive income		225
Net current-period other comprehensive income		225
Balance at end of period	(12,521)	(12,296)
Accumulated Other Comprehensive Income | As Reported
Rollforward of accumulated other comprehensive income (loss), net of tax
Balance at beginning of period	16,550	$ 16,550
Accumulated Other Comprehensive Income | ASU 2016-01 | Adjustments
Rollforward of accumulated other comprehensive income (loss), net of tax
Adoption of ASU No. 2016-01 (1)	$ (29,071)