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Income Taxes (Details 3) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Tax credit and operating loss carryforwards |  |  |  |
Unrecognized tax benefits, reduction of long-term deferred tax assets, before federal tax benefit |  | $ 20,400 | $ 19,700 |
Unrecognized tax benefits included in long-term income taxes payable |  | 2,200 | 2,200 |
Portion of unrecognized tax benefits, which if recognized, would be recorded as an income tax benefit |  | 2,200 | 2,200 |
Amount of potential unrecognized tax benefit |  | 200 |  |
Reconciliation of the beginning and ending amounts of unrecognized income tax benefits |  |  |  |
Balance at the beginning of the period | $ 22,652 | 21,925 | 20,836 | $ 19,903
Tax positions related to current year: |  |  |  |
Additions |  | 1,083 | 1,225 | 1,186
Tax positions related to prior years: |  |  |  |
Additions |  | 16 | 256 | 0
Reductions |  | (372) | (171) | (35)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities |  | 0 | (221) | (218)
Balance at the end of the period |  | 22,652 | $ 21,925 | $ 20,836
Undistributed earnings |  | $ 11,500 |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  | 35.00% | 35.00% | 35.00%
Alternative Minimum Tax Credits |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Tax credit carryforwards |  | $ 2,500 |  |
Foreign Tax Credit |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Tax credit carryforwards |  | 116,500 |  |
2017 U.S.Tax Reform Member [Member] |  |  |  |
Tax positions related to prior years: |  |  |  |
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount |  | 20,700 |  |
Federal | Research and Development as label |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Tax credit carryforwards |  | 38,000 |  |
Federal | Foreign Tax Credit |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Tax Credit Carryforward, Subject To Expiration, Amount |  | 54,900 |  |
State and Local Jurisdiction [Member] |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Operating Loss Carryforwards |  | 125,000 |  |
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member] |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Operating Loss Carryforwards |  | 195,400 |  |
Operating Loss Carryforwards, Expired |  | 67,100 |  |
Operating Loss Carryforwards, Expiring in the Future |  | 21,500 |  |
State and Local Jurisdiction [Member] | Research and Development as label |  |  |  |
Tax credit and operating loss carryforwards |  |  |  |
Tax credit carryforwards |  | $ 27,000 |  |
Scenario, Forecast [Member] |  |  |  |
Tax positions related to prior years: |  |  |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent | 21.00% |  |  |

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