CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net income	$ 113,654	$ 45,522	$ 246,730	$ 105,504
Other comprehensive (loss) income, net of tax (note 9):
Change in unrealized investment gains and losses (note 7)	(63,646)	44,501	(44,083)	84,099
Benefit plan adjustments	(392)	(1,980)	(1,092)	(3,466)
Foreign currency translation adjustment	390	587	(1,624)	1,840
Other comprehensive (loss) income, net of tax	(63,648)	43,108	(46,799)	82,473
Comprehensive income	$ 50,006	$ 88,630	$ 199,931	$ 187,977