Goodwill and Other Intangible Assets (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 469,433,000	$ 469,433,000	$ 469,433,000	$ 469,433,000	$ 469,433,000
Number of operating segments | segment			3
Goodwill impairment					$ 0
Finite-Lived Intangible Assets [Line Items]
Amortization expense	1,735,000	2,023,000	$ 5,314,000	6,177,000
Core Deposit Intangibles
Finite-Lived Intangible Assets [Line Items]
Impairment write-downs			0	0
Amortization expense	$ 1,700,000	$ 2,000,000	$ 5,300,000	$ 6,200,000