Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Schedule of assets and liabilities measured at fair vale on a recurring basis

All fair value measurements at the reporting date were on a recurring basis.



December 31, 2016 (In thousands)	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Recurring fair value measurements
Financial Assets:
U.S. Treasury securities	$	191,548	$	—	$	—	$	191,548
U.S. agency securities	—		18,441		—		18,441
U.S. agency mortgage-backed securities	—		316,494		—		316,494
Municipal debt securities	—		334,324		—		334,324
Corporate debt securities	—		456,357		—		456,357
Residential and commercial mortgage securities	—		68,336		—		68,336
Asset-backed securities	—		127,172		—		127,172
Money market funds	102,430		—		—		102,430
Total assets at fair value	$	293,978	$	1,321,124	$	—	$	1,615,102
Financial Liabilities:
Derivative liabilities	$	—	$	—	$	—	$	—
Total liabilities at fair value	$	—	$	—	$	—	$	—



December 31, 2015 (In thousands)	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Recurring fair value measurements
Financial Assets:
U.S. Treasury securities	$	177,607	$	—	$	—	$	177,607
U.S. agency securities	—		13,782		—		13,782
U.S. agency mortgage-backed securities	—		159,602		—		159,602
Municipal debt securities	—		279,828		—		279,828
Corporate debt securities	—		396,732		—		396,732
Residential and commercial mortgage securities	—		55,356		—		55,356
Asset-backed securities	—		126,629		—		126,629
Money market funds	67,098		—		—		67,098
Total assets at fair value	$	244,705	$	1,031,929	$	—	$	1,276,634
Financial Liabilities:
Derivative liabilities	$	—	$	—	$	1,232	$	1,232
Total liabilities at fair value	$	—	$	—	$	1,232	$	1,232

Schedule of changes during period in Level 3 liabilities measured at fair value on a recurring basis, and realized and unrealized losses (gains) related to Level 3 liabilities

The following table presents changes during the years ended December 31, 2016 and 2015 in Level 3 liabilities measured at fair value on a recurring basis, and the net realized and unrealized losses (gains) related to the Level 3 liabilities in the consolidated balance sheets at December 31, 2016 and 2015. During the years ended December 31, 2016 and 2015, we had no Level 3 assets.



	Year Ended December 31,
(In thousands)	2016			2015
Level 3 Liabilities
Fair value of derivative liabilities at beginning of period	$	1,232		$	661
Net realized and unrealized losses (gains) included in income	(1,934		)	(1,092		)
Other comprehensive (income) loss	—			—
Purchases, sales, issues and settlements, net	702			1,663
Gross transfers in	—			—
Gross transfers out	—			—
Fair value of derivative liabilities at end of period	$	—		$	1,232

Changes in net unrealized losses (gains) included in income on instruments held at end of period	$	(1,934	)	$	(1,092	)

Summary of significant unobservable inputs used in recurring Level 3 fair value measurements

The following table summarizes the significant unobservable inputs used in our recurring Level 3 fair value measurements as of December 31, 2015:



December 31, 2015
($ in thousands)	Fair Value		Valuation Technique	Unobservable Input	Weighted Average
Derivative Liabilities	$	1,232	Discounted cash flows	Constant prepayment rate	10.60	%
				Default rate	0.50	%
				Reference STACR credit spread	3.93	%