Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	[1]		$ (345)
Equity Securities, FV-NI		$ 9,801		$ 0
ASU 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 2,200

[1] Cumulative-effect adjustment to beginning retained earnings for fair value adjustments related to the reclassification of certain equity investments in accordance with ASU 2016-01, adopted as of January 1, 2018.