Fair Value Measurement (Changes in Level 3 Table) (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015		Jun. 30, 2016	Jun. 30, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale securities, Beginning balance		$ 334,157	$ 346,685		$ 341,644	$ 339,187
Available-for-sale securities, (Gains) losses included in earnings	[1]	0	0		0	0
Available-for-sale securities, Unrealized gains (losses)	[2]	8,926	4,561		1,370	11,697
Available-for-sale securities, Purchases		0	41,509		0	41,509
Available-for-sale securities, Sales		0	(71,832)		0	(71,832)
Available-for-sale securities, Settlements		(179)	(9,387)		(110)	(9,025)
Available-for-sale securities, Ending balance		342,904	311,536		342,904	311,536
True-up liability, Beginning balance		15,115	13,707		14,750	13,294
True-up liability, (Gains) losses included in earnings		(1,055)	299	[1]	(1,420)	(114)	[1]
True-up liability, Unrealized gains (losses)	[2]	0	0		0	0
True-up liability, Purchases		0	0		0	0
True-up liability, Sales		0	0		0	0
True-up liability, Settlements		0	0		0	0
True-up liability, Ending balance		$ 16,170	$ 13,408		$ 16,170	$ 13,408

[1] Reported in "Other expense

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