CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Securities, available-for-sale, at fair value:
Fixed maturities, amortized cost	$ 4,586,317	$ 4,602,514
Shareholders' equity (note 14):
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares issued (in shares)	340,079	340,047
Common stock, shares outstanding (in shares)	339,639	338,560
Treasury stock, shares at cost (in shares)	440	1,487