Investments Schedule of Available for sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017		Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 1,182,427		$ 1,283,161
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	5,072		4,635
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	17,171		23,664
Available-for-sale Securities	1,170,328		1,264,132
Held-to-maturity Securities	74,576		93,079
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0		1
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(795)		(476)
Held-to-maturity Securities, Fair Value	73,781		92,604
U.S. government and agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	35,132	[1]	40,704
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0		86
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	833		854
Available-for-sale Securities	34,299	[1]	39,936
Government-sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	305,101	[1]	337,865
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	22		1,058
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,622		2,259
Available-for-sale Securities	302,501	[1]	336,664
Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	299,647	[1]	296,271
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,559		2,116
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,148		4,990
Available-for-sale Securities	303,058	[1]	293,397
Mortgage-backed securities (1)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	521,753	[2]	584,960	[3]
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	491		928	[3]
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	12,568		15,561	[3]
Available-for-sale Securities	509,676	[2]	570,327	[3]
Held-to-maturity Securities	74,576	[2]	93,079	[3]
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0		1	[3]
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(795)		(476)	[3]
Held-to-maturity Securities, Fair Value	73,781	[2]	92,604	[3]
Other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	20,794	[4]	23,361
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0		447
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0		0
Available-for-sale Securities	$ 20,794	[4]	$ 23,808

[1] Certain securities are callable before their final maturity.

[2] Mortgage-backed securities are shown based on their final (contractual) maturity, but, due to prepayments, they are expected to have shorter lives.

[3] All mortgage-backed securities are guaranteed by U.S. government agencies or Government-sponsored entities.

[4] Other securities consist of money market mutual funds and equity securities held by certain Wealth Advisory and Investment Management businesses.