Stockholders' Equity - Changes in Accumulated Other Comprehensive Income, Net of Tax by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (4,667)	$ 11,437	$ (75)	$ 10,753
Other comprehensive income (loss) before reclassifications	(4,385)	(4,170)	(5,294)	(866)
Amounts reclassified from accumulated other comprehensive income	(1,186)	(1,546)	(4,869)	(4,166)
Other Comprehensive income (loss), net of tax	(5,571)	(5,716)	(10,163)	(5,032)
Ending balance	(10,238)	5,721	(10,238)	5,721
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	6,678	11,035	8,964	10,737
Other comprehensive income (loss) before reclassifications	(3,034)	(1,602)	(1,497)	1,316
Amounts reclassified from accumulated other comprehensive income	(1,257)	(1,546)	(5,080)	(4,166)
Other Comprehensive income (loss), net of tax	(4,291)	(3,148)	(6,577)	(2,850)
Ending balance	2,387	7,887	2,387	7,887
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(5,617)	(891)	(5,757)	(891)
Amounts reclassified from accumulated other comprehensive income	71		211
Other Comprehensive income (loss), net of tax	71		211
Ending balance	(5,546)	(891)	(5,546)	(891)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(5,728)	1,293	(3,282)	907
Other comprehensive income (loss) before reclassifications	(1,351)	(2,568)	(3,797)	(2,182)
Other Comprehensive income (loss), net of tax	(1,351)	(2,568)	(3,797)	(2,182)
Ending balance	$ (7,079)	$ (1,275)	$ (7,079)	$ (1,275)