Fair Value Measurement and Fair Value of Financial Instruments (Reconciliation of Assets and Liabilities Measured on Recurring Basis) (Details) - Fair Value, Measurements, Recurring - Significant Unobservable Inputs (Level 3) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2016
Reconciliation of the beginning and ending balances for major asset categories measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Beginning balance	$ 0
Purchases, issues, sales, settlements:
Liabilities measured using significant unobservable inputs on a recurring basis			$ 0
Warrants
Reconciliation of the beginning and ending balances for major liability categories measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Beginning balance	0
Total gains (losses) for the period:
Included in earnings	0
Included in other comprehensive income	0
Purchases, issues, sales, settlements:
Issuances	679,000
Sales	0
Settlements	0
Transfers out of Level 3	0
Ending balance	679,000
Embedded Derivative Liabilities
Reconciliation of the beginning and ending balances for major liability categories measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Beginning balance		$ (3,392,000)
Total gains (losses) for the period:
Included in earnings		(20,000)
Included in other comprehensive income		0
Purchases, issues, sales, settlements:
Issuances		0
Sales		0
Settlements		3,412,000
Transfers out of Level 3		0
Ending balance		0
Other securities
Reconciliation of the beginning and ending balances for major asset categories measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Beginning balance	0
Transfer from held-to-maturity investment security to available-for-sale investment security	115,615,000
Total gains (losses) for the period:
Included in earnings	1,156,000
Included in other comprehensive income	0
Purchases, issues, sales, settlements:
Issuances	0
Sales	116,771,000
Settlements	0
Transfers out of Level 3	0
Ending balance	$ 0
Corporate debt securities | Non-investment grade
Reconciliation of the beginning and ending balances for major asset categories measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Beginning balance		6,528,000
Total gains (losses) for the period:
Included in earnings		960,000
Included in other comprehensive income		922,000
Purchases, issues, sales, settlements:
Issuances		0
Sales		7,219,000
Settlements		98,000
Transfers out of Level 3		(1,093,000)
Ending balance		$ 0