Fair Value Measurements Fair Value Hierarchy (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | $ 148,548 | $ 153,509 |
Certificates of Deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 5,000 | |
Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | | 1,000 |
US treasury notes [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 10,875 | 10,875 |
Agencies securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 4,940 | |
Municipal bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 589 | 739 |
Asset-backed securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 11,211 | 20,861 |
Recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 148,548 | 153,509 |
Contingent consideration, fair value | 17,156 | 17,358 |
Recurring [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Contingent consideration, fair value | 0 | 0 |
Recurring [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 148,548 | 153,509 |
Contingent consideration, fair value | 0 | 0 |
Recurring [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Contingent consideration, fair value | 17,156 | 17,358 |
Recurring [Member] | Certificates of Deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 5,000 | |
Recurring [Member] | Certificates of Deposit [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | |
Recurring [Member] | Certificates of Deposit [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 5,000 | |
Recurring [Member] | Certificates of Deposit [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | |
Recurring [Member] | Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | | 1,000 |
Recurring [Member] | Corporate bonds [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | | 0 |
Recurring [Member] | Corporate bonds [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | | 1,000 |
Recurring [Member] | Corporate bonds [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | | 0 |
Recurring [Member] | US treasury notes [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 10,875 | 10,875 |
Recurring [Member] | US treasury notes [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | US treasury notes [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 10,875 | 10,875 |
Recurring [Member] | US treasury notes [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | Agencies securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 4,940 | |
Recurring [Member] | Agencies securities [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | |
Recurring [Member] | Agencies securities [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 4,940 | |
Recurring [Member] | Agencies securities [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | |
Recurring [Member] | Mortgage-backed securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 115,933 | 120,034 |
Recurring [Member] | Mortgage-backed securities [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | Mortgage-backed securities [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 115,933 | 120,034 |
Recurring [Member] | Mortgage-backed securities [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | Municipal bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 589 | 739 |
Recurring [Member] | Municipal bonds [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | Municipal bonds [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 589 | 739 |
Recurring [Member] | Municipal bonds [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | Asset-backed securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 11,211 | 20,861 |
Recurring [Member] | Asset-backed securities [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 0 | 0 |
Recurring [Member] | Asset-backed securities [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | 11,211 | 20,861 |
Recurring [Member] | Asset-backed securities [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value | $ 0 | $ 0 |