Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of available-for-sale securities

The following is a summary of available-for-sale securities at December 31:

($ in thousands)		2018				2017
Marketable Securities:	Fair Value Hierarchy	Cost		Estimated Fair Value		Cost		Estimated Fair Value
Certificates of deposit
with unrecognized losses for less than 12 months		$	250	$	248	$	6,238	$	6,222
with unrecognized losses for more than 12 months		3,861		3,812		102		100
with unrecognized gains		—		—		2,088		2,089
Total Certificates of deposit	Level 1	4,111		4,060		8,428		8,411
U.S. Treasury and agency notes
with unrecognized losses for less than 12 months		3,112		3,105		29,741		29,669
with unrecognized losses for more than 12 months		23,564		23,415		137		135
with unrecognized gains		3		4		152		153
Total U.S. Treasury and agency notes	Level 2	26,679		26,524		30,030		29,957
Corporate notes
with unrecognized losses for less than 12 months		13,696		13,665		18,230		18,159
with unrecognized losses for more than 12 months		12,542		12,431		2,804		2,788
Total Corporate notes	Level 2	26,238		26,096		21,034		20,947
Municipal notes
with unrecognized losses for less than 12 months		2,994		2,982		10,298		10,288
with unrecognized losses for more than 12 months		4,116		4,087		999		987
with unrecognized gains		—		—		277		278
Total Municipal notes	Level 2	7,110		7,069		11,574		11,553
		$	64,138	$	63,749	$	71,066	$	70,868

Summary of maturities, at par, of marketable securities by year

The following tables summarize the maturities, at par, of marketable securities by year ($ in thousands):

December 31, 2018	2019		2020		2021		2022		Total
Certificates of deposit	$	2,311	$	1,799	$	—	$	—	$	4,110
U.S. Treasury and agency notes	17,574		9,174		—		—		26,748
Corporate notes	18,671		7,150		400		—		26,221
Municipal notes	5,111		2,000		—		—		7,111
	$	43,667	$	20,123	$	400	$	—	$	64,190

December 31, 2017	2018		2019		2020		2021		Total
Certificates of deposit	$	4,306	$	2,311	$	1,799	$	—	$	8,416
U.S. Treasury and agency notes	6,399		14,599		9,171		—		30,169
Corporate notes	7,954		6,430		6,450		—		20,834
Municipal notes	1,568		6,957		3,003		—		11,528
	$	20,227	$	30,297	$	20,423	$	—	$	70,947