Fair Value Measurement (Changes in Level 3 Table) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Available-for-sale securities, Beginning balance		$ 341,644	$ 339,187
Available-for-sale securities, (Gains) losses included in earnings	[1]	0	0
Available-for-sale securities, Unrealized gains (losses)	[2]	(7,556)	6,682
Available-for-sale securities, Purchases		0	$ 0
Available-for-sale securities, Sales		0
Available-for-sale securities, Settlements		69	$ 362
Available-for-sale securities, Ending balance		334,157	346,231
True-up liability, Beginning balance		14,750	13,294
True-up liability, (Gains) losses included in earnings		365	413	[1]
True-up liability, Unrealized gains (losses)	[2]	0	0
True-up liability, Purchases		0	$ 0
True-up liability, Sales		0
True-up liability, Settlements		0	$ 0
True-up liability, Ending balance		$ 15,115	$ 13,707

[1] Reported in "Other expense

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