Fair Value Measurement (Changes in Level 3 Table) (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014		Jun. 30, 2015	Jun. 30, 2014
Fair Value Disclosures [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		$ 41,509	$ 0		$ 41,509	$ 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		(71,832)	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		346,685	349,425		339,187	347,610
True-up liability, Beginning balance		13,707	11,983		13,294	11,463
Available-for-sale securities, Total unrealized gains/losses	[1]	0	0		0	0
True-up liability, Total unrealized gains/losses		(299)	598	[1]	114	1,118	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[2]	4,561	1,253		11,697	3,021
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		(9,387)	55		(9,025)	102
True-up liability, Settlements		0	0		0	0
Available-for-sale securities, Ending balance		311,536	350,733		311,536	350,733
True-up liability, Ending balance		$ 13,408	$ 12,581		$ 13,408	$ 12,581

[1] Reported in "Other expense

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