Consolidated Statements Of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net unrealized holding gains (losses) on investments arising during the period, tax provision (benefit)	$ 5,907	$ (522)
Less: reclassification adjustment for net (gains) losses included in net income (loss), tax provision (benefit)	(11)	14
Net change in unrealized holding gains (losses) on investments, tax provision (benefit)	5,918	(536)
Net unrealized foreign exchange gains (losses) arising during the period, tax provision (benefit)	1,511	3,236
Less: reclassification adjustment for foreign exchange (gains) losses included in net income (loss), tax provision (benefit)	1,097	0
Net change in unrealized foreign exchange gains (losses), tax provision (benefit)	414	3,236
Net unrealized gains (losses) on instrument specific credit risk arising during the period, tax provision (benefit)	(6,345)	0
Less: reclassification adjustment for instrument specific credit risk (gains) losses included in net income (loss), tax provision (benefit)	0	0
Net change in unrealized instrument specific credit risk gains (losses), tax provision (benefit)	(6,345)	0
Net pension gains (losses) arising during the period, tax provision (benefit)	0	0
Less: reclassification adjustment for pension (gains) losses included in net income (loss), tax provision (benefit)	(1,435)	(178)
Net change in pension liability, tax provision (benefit)	$ 1,435	$ 178