CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net (loss) income:	$ (1,971)	$ 406,282	$ 4,966
Available-for-sale investment items:
Net unrealized gains (losses) on available-for-sale investments	5,650	(1,455)	(2,032)
Reclassification of other-than-temporary impairment losses included in earnings	0	1,295	0
Reclassification of realized (gains) losses included in earnings	(5,311)	833	(93)
Total before income taxes	339	673	(2,125)
Income tax	300	127	0
Total	639	800	(2,125)
Defined benefit pension items:
Net (loss) gain arising during the period	0	(2,180)	2,191
Amortization and settlement included in net periodic cost	0	7,107	743
Amortization of loss included in net periodic cost	0	465	326
Total before income taxes	0	5,392	3,260
Income tax	0	0	0
Total	0	5,392	3,260
Total other comprehensive income, net of tax	639	6,192	1,135
Total comprehensive (loss) income	$ (1,332)	$ 412,474	$ 6,101