Nature of Business and Summary of Significant Accounting Policies (Other Comprehensive Income) - Changes in Accumulated Other Comprehensive Income, Net of Tax by Component (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (75)	$ 10,753	$ 11,268
Other comprehensive income (loss) before reclassifications	(2,979)	(6,692)	4,364
Amounts reclassified from accumulated other comprehensive income	(5,915)	(4,136)	(4,879)
Ending balance	(8,969)	(75)	10,753
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	8,964	10,737	10,108
Other comprehensive income (loss) before reclassifications	(844)	2,363	5,508
Amounts reclassified from accumulated other comprehensive income	(6,188)	(4,136)	(4,879)
Ending balance	1,932	8,964	10,737
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(5,757)	(891)	(1,952)
Other comprehensive income (loss) before reclassifications	1,589	(4,866)	1,061
Amounts reclassified from accumulated other comprehensive income	273
Ending balance	(3,895)	(5,757)	(891)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(3,282)	907	3,112
Other comprehensive income (loss) before reclassifications	(3,724)	(4,189)	(2,205)
Ending balance	$ (7,006)	$ (3,282)	$ 907