Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current Deferred Tax Assets (Liabilities):
U.S. federal and state net operating loss carryforwards	$ 344,000	$ 8,909,000
Capitalized research and development costs	10,507,000	8,921,000
Accruals, reserves and other	24,661,000	25,374,000
Valuation allowance	(5,358,000)	(4,988,000)
Current deferred tax assets (liabilities), net	30,154,000	38,216,000
Noncurrent Deferred Tax Assets (Liabilities):
State net operating loss carryforwards	432,000	1,136,000
Capitalized research and development costs	0	15,847,000
Tax credit/capital loss carryforwards and other	15,375,000	18,296,000
Excess tax depreciation and other	(40,591,000)	(42,602,000)
Valuation allowance	(1,827,000)	(3,556,000)
Noncurrent deferred tax (liabilities) assets, net	(26,611,000)	(10,879,000)
Total deferred tax assets, net	3,543,000	27,337,000
Current:
Federal	7,573,000	1,889,000	384,000
State	2,858,000	1,862,000	841,000
Foreign	61,000	102,000	115,000
Total current	10,492,000	3,853,000	1,340,000
Deferred:
Federal	25,667,000	29,264,000	29,558,000
State	(904,000)	(2,339,000)	(10,259,000)
Total deferred	24,763,000	26,925,000	19,299,000
Total income tax provision	35,255,000	30,778,000	20,639,000
Effective income tax rate reconciliation [Abstract]
U.S. federal statutory rate (in hundredths)	35.00%	35.00%	35.00%
State taxes (in hundredths)	3.30%	3.60%	3.30%
Domestic manufacturing deduction	(2.10%)	0.00%	0.00%
Extraterritorial income exclusion (in hundredths)	(1.00%)	(3.10%)	(8.70%)
Research and development credits (in hundredths)	(0.70%)	(1.70%)	(4.50%)
Other, net (in hundredths)	(0.50%)	(0.30%)	(1.70%)
Effective rate (in hundredths)	34.00%	33.50%	23.40%
Capital Loss Carryforwards [Line Items]
Capital loss carryforwards	17,400,000
Reconciliation of unrecognized tax benefits [Roll Forward]
Unrecognized tax benefits at beginning of year	18,200,000	16,732,000	12,386,000
Additions based on tax positions related to the current year	0	0	2,325,000
Additions for tax positions of prior years	646,000	1,548,000	2,351,000
Reduction resulting from lapse of statute of limitation	(10,000)	(80,000)	(330,000)
Unrecognized tax benefits at end of year	18,836,000	18,200,000	16,732,000
Income before income taxes from foreign income	200,000	300,000	400,000
Extraterritorial income exclusion	$ 1,100,000	$ 2,800,000	$ 7,700,000
U.S. Federal [Member] | Minimum [Member]
Capital Loss Carryforwards [Line Items]
Expiration of capital loss carryforwards	Dec. 31, 2015
U.S. Federal [Member] | Maximum [Member]
Capital Loss Carryforwards [Line Items]
Expiration of capital loss carryforwards	Dec. 31, 2018