Income Taxes (Details Textual) - USD ($) $ in Thousands, shares in Millions		12 Months Ended
	Oct. 06, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statutory Federal Income Tax Rate		35.00%
Income Taxes Receivable		$ 98,800
Taxes Payable, Current			$ 7,400
Deferred Tax Assets, Valuation Allowance		94,120	100,920
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense		6,300
Unused Federal operating loss carryforwards		0
Unused State operating loss carryforwards		1,100,000
Unused Federal capital loss carryforwards		33,500
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		5,700
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit			1,500
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		200	(600)	$ (2,400)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		500	300
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		13,071	(8,689)	$ (2,917)
Valuation Allowances and Reserves, Period Increase (Decrease)		$ (6,800)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent		21.00%
Minimum [Member]
State operating loss carryforwards expiration date		Dec. 31, 2018
Open Tax Year		2009
Maximum [Member]
State operating loss carryforwards expiration date		Dec. 31, 2037
Federal capital loss carryforward expiration date		12/31/2021
Foreign tax credit carryforward expiration date		Dec. 31, 2021
Open Tax Year		2016
State and Local Jurisdiction [Member] | Minimum [Member]
Income Tax Examination, Year under Examination		2009
State and Local Jurisdiction [Member] | Maximum [Member]
Income Tax Examination, Year under Examination		2015
Internal Revenue Service (IRS) [Member] | Minimum [Member]
Income Tax Examination, Year under Examination		2011
Internal Revenue Service (IRS) [Member] | Maximum [Member]
Income Tax Examination, Year under Examination		2012
Shares Of Common Stock [Member] | Square 1 Financial, Inc. [Member]
Stock Issued During Period, Shares, New Issues	18.1
Unrecognized Tax Rate Benefit (Negative Benefit) [Member]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		$ 2,200	$ 1,100
Expires 2018 [Member]
Unused Federal capital loss carryforwards		30,500
Valuation Allowance, Tax Credit Carryforward [Member]
Valuation Allowances and Reserves, Period Increase (Decrease)		$ (11,600)