Investments Maturities of Available for sale Securities by Type (Details) - USD ($) $ in Thousands		12 Months Ended
		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		$ 1,170,328		$ 1,264,132
Weighted Average Remaining Maturity, Available for Sale Securities		8 years 20 days		9 years 1 month 20 days
Available for Sale Securities Callable Before Maturity		$ 184,900		$ 140,400
U.S. government and agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	[1]	0
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	[1]	$ 0
Available for sale Securities, Maturities, Next Twelve Months, Weighted Average Yield	[1]	0.00%
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	[1]	$ 15,192
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	[1]	$ 15,105
Available for sale Securities, Maturities, Year Two Through Five, Weighted Average Yield	[1]	1.53%
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	[1]	$ 19,940
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	[1]	$ 19,194
Available for sale Securities, Maturities, Year Six Through Ten, Weighted Average Yield	[1]	1.73%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	[1]	$ 0
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	[1]	$ 0
Available for sale Securities, Maturities, After Ten Years, Weighted Average Yield	[1]	0.00%
Available-for-sale Securities, Amortized Cost Basis		$ 35,132	[1]	40,704
Available-for-sale Securities		$ 34,299	[1]	39,936
Available for sale Securities, Weighted Average Yield	[1]	1.64%
Government-sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	[1]	$ 44,033
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	[1]	$ 43,967
Available for sale Securities, Maturities, Next Twelve Months, Weighted Average Yield	[1]	1.39%
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	[1]	$ 224,747
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	[1]	$ 223,315
Available for sale Securities, Maturities, Year Two Through Five, Weighted Average Yield	[1]	1.86%
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	[1]	$ 36,321
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	[1]	$ 35,219
Available for sale Securities, Maturities, Year Six Through Ten, Weighted Average Yield	[1]	2.05%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	[1]	$ 0
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	[1]	$ 0
Available for sale Securities, Maturities, After Ten Years, Weighted Average Yield	[1]	0.00%
Available-for-sale Securities, Amortized Cost Basis		$ 305,101	[1]	337,865
Available-for-sale Securities		$ 302,501	[1]	336,664
Available for sale Securities, Weighted Average Yield	[1]	1.81%
Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	[1]	$ 15,770
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	[1]	$ 15,756
Available for sale Securities, Maturities, Next Twelve Months, Weighted Average Yield	[1],[2]	1.85%
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	[1]	$ 57,178
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	[1]	$ 57,260
Available for sale Securities, Maturities, Year Two Through Five, Weighted Average Yield	[1],[2]	2.63%
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	[1]	$ 33,979
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	[1]	$ 34,719
Available for sale Securities, Maturities, Year Six Through Ten, Weighted Average Yield	[1],[2]	3.73%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	[1]	$ 192,720
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	[1]	$ 195,323
Available for sale Securities, Maturities, After Ten Years, Weighted Average Yield	[1],[2]	4.07%
Available-for-sale Securities, Amortized Cost Basis		$ 299,647	[1]	296,271
Available-for-sale Securities		$ 303,058	[1]	293,397
Available for sale Securities, Weighted Average Yield	[1],[2]	3.64%
Mortgage-backed securities (1)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	[3]	$ 17
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	[3]	$ 17
Available for sale Securities, Maturities, Next Twelve Months, Weighted Average Yield	[3]	2.33%
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	[3]	$ 11,460
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	[3]	$ 11,407
Available for sale Securities, Maturities, Year Two Through Five, Weighted Average Yield	[3]	2.25%
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	[3]	$ 236,360
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	[3]	$ 229,770
Available for sale Securities, Maturities, Year Six Through Ten, Weighted Average Yield	[3]	2.18%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	[3]	$ 273,916
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	[3]	$ 268,482
Available for sale Securities, Maturities, After Ten Years, Weighted Average Yield	[3]	2.10%
Available-for-sale Securities, Amortized Cost Basis		$ 521,753	[3]	584,960	[4]
Available-for-sale Securities		$ 509,676	[3]	570,327	[4]
Available for sale Securities, Weighted Average Yield	[3]	2.14%
Other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	[5]	$ 20,794
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	[5]	$ 20,794
Available for sale Securities, Maturities, Next Twelve Months, Weighted Average Yield	[5]	0.00%
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	[5]	$ 0
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	[5]	$ 0
Available for sale Securities, Maturities, Year Two Through Five, Weighted Average Yield	[5]	0.00%
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	[5]	$ 0
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	[5]	$ 0
Available for sale Securities, Maturities, Year Six Through Ten, Weighted Average Yield	[5]	0.00%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	[5]	$ 0
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	[5]	$ 0
Available for sale Securities, Maturities, After Ten Years, Weighted Average Yield	[5]	0.00%
Available-for-sale Securities, Amortized Cost Basis		$ 20,794	[5]	23,361
Available-for-sale Securities		$ 20,794	[5]	$ 23,808
Available for sale Securities, Weighted Average Yield	[5]	0.00%

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

[2] Yields shown on a fully taxable equivalent (“FTE”) basis. The tax rate used in the table above was the tax rate in effect on December 31, 2017. The recent enactment of the Tax Act will reduce the rate applied in future periods, which will result in a lower FTE yield.

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

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

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