Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) plan	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of compensation plans | plan	3
Award vesting period (in years)	4 years
ESPP, market price discount percentage	5.00%
Available-for-Sale	$ 317,535	$ 300,200
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments to additional paid in capital, income tax rate reduction		1,600
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of ASU adoption		(102)
Fair Value, Measurements, Recurring
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Available-for-Sale	$ 317,535	300,200
Equity Securities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Available-for-Sale		1,561
Equity Securities | Fair Value, Measurements, Recurring
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Available-for-Sale		$ 1,561
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible asset, useful life (in years)	10 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible asset, useful life (in years)	15 years
Building and Building Improvements | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	20 years
Building and Building Improvements | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	40 years
Furniture and Fixtures | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	7 years
Furniture and Fixtures | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	10 years
Computer Equipment | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	5 years
Computer Equipment | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	7 years
Equity Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Award vesting period (in years)	4 years
Restricted Stock Units (RSUs)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Award vesting period (in years)	3 years
Scenario, Forecast | Subsequent Event | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right of use asset			$ 8,000
Operating lease, liability			$ 8,000