Recent Accounting Developments (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrealized gain from securities	$ 1,030	$ 0
Change in interest income hedge effectiveness	$ 45
Provisional tax benefit recognized			$ 7,600
ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				$ 0
ASU 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(116)
ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				0
Retained earnings | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				1,880
Retained earnings | ASU 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(116)
Retained earnings | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				2,974
Accumulated other comprehensive loss | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(1,880)
Accumulated other comprehensive loss | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				(2,974)
New Accounting Pronouncement, Early Adoption, Effect | Retained earnings | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				3,000
New Accounting Pronouncement, Early Adoption, Effect | Accumulated other comprehensive loss | ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment				$ (3,000)