Stockholders' Equity - Changes in Accumulated Other Comprehensive Income, Net of Tax by Component (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement Of Income And Comprehensive Income [Abstract]
Unrealized Gains (Losses) on Available-for-Sale Securities, Beginning balance	$ 10,108	$ 10,160
Unrealized Gains (Losses) on Available-for-Sale Securities, Other comprehensive income (loss) before reclassifications	454	8,205
Unrealized Gains (Losses) on Available-for-Sale Securities, Amounts reclassified from accumulated other comprehensive income	(2,098)	(1,448)
Unrealized Gains (Losses) on Available-for-Sale Securities, Net current period other comprehensive income (loss)	(1,644)	6,757
Unrealized Gains (Losses) on Available-for-Sale Securities, Ending balance	8,464	16,917
Defined Benefit Plan Adjustments, Beginning balance	(1,952)
Defined Benefit Plan Adjustments, Other comprehensive income (loss) before reclassifications
Defined Benefit Plan Adjustments, Amounts reclassified from accumulated other comprehensive income
Defined Benefit Plan Adjustments, Net current period other comprehensive income (loss)
Defined Benefit Plan Adjustments, Ending balance	(1,952)
Foreign Currency Adjustments, Beginning balance	3,112	2,942
Foreign Currency Adjustments, Other comprehensive income (loss) before reclassifications	323	153
Foreign Currency Adjustments, Amounts reclassified from accumulated other comprehensive income
Foreign Currency Adjustments, Net current period other comprehensive income (loss)	323	153
Foreign Currency Adjustments, Ending balance	3,435	3,095
Beginning balance, Total	11,268	13,102
Other comprehensive income (loss) before reclassifications, Total	777	8,358
Amounts reclassified from accumulated other comprehensive income, Total	(2,098)	(1,448)
Other Comprehensive Income (Loss), net of tax	(1,321)	6,910
Ending balance, Total	$ 9,947	$ 20,012