Fair Value Measurement (Changes in Level 3 Table) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014		Sep. 30, 2015	Sep. 30, 2014
Fair Value Disclosures [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		$ 37,937	$ 0		$ 79,446	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases		0	0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	0		(71,832)	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales		0	0		0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale securities, Beginning balance		311,536	350,733		339,187	347,610
True-up liability, Beginning balance		13,408	12,581		13,294	11,463
Available-for-sale securities, Total unrealized gains/losses	[1]	0	0		0	0
True-up liability, Total unrealized gains/losses		164	223	[1]	278	1,341	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[2]	(3,627)	277		8,070	3,298
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	[2]	0	0		0	0
Available-for-sale securities, Settlements		1,147	(3,489)		(7,878)	(3,387)
True-up liability, Settlements		0	0		0	0
Available-for-sale securities, Ending balance		346,993	347,521		346,993	347,521
True-up liability, Ending balance		$ 13,572	$ 12,804		$ 13,572	$ 12,804

[1] Reported in "Other expense

[2] Reported in "Other comprehensive income (loss)