Stockholders' Equity (Reclassifications in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision for income taxes, investments	$ 6,552	$ (60,033)	$ (129,332)	$ (236,824)
Total reclassifications for the period	51,477	(451)	51,890	1,114
Benefits Liability, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassifications for the period	(228)	(451)	(661)	(1,318)
Net Unrealized Holdings Gains on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income (loss), including portion attributable to noncontrolling interest	51,705	0	52,551	2,432
Total reclassifications for the period			52,551	2,432
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of pension and other post-retirement items, net loss	(369)	(692)	(1,072)	(2,019)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Benefits Liability, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision for income taxes, defined benefit plan	141	241	411	701
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Unrealized Holdings Gains on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income, net	52,401	0	53,720	3,795
Provision for income taxes, investments	$ (696)	$ 0	$ (1,169)	$ (1,363)