Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 56,740	$ 65,531
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	4,500	700
Depreciation, amortization, and accretion, net	14,363	5,563
Deferred income taxes	6,816	15,798
Stock compensation	1,622
Other gains	(142)	(9)
Net gains on sales of loans held for sale	(12)
Net gains on investment securities		(25,728)
Change in assets and liabilities:
Net decrease in other assets	14,761	1,933
Net decrease in other liabilities	(33,625)	(11,630)
Net cash provided by operating activities	65,023	52,158
Available-for-sale securities:
Proceeds from maturities and principal repayments	205,927	241,472
Proceeds from sales		534,557
Purchases	(390,968)	(520,399)
Other investments:
Proceeds from sales	8,452	6,725
Purchases	(5,858)	(6,764)
Net increase in loans and leases resulting from originations and principal repayments	(265,066)	(239,385)
Proceeds from sales of loans originated for investment	671
Proceeds from bank owned life insurance	3,987	455
Purchases of premises, equipment, and software	(1,032)	(4,234)
Proceeds from sales of premises and equipment	10
Proceeds from sales of other real estate owned	635	167
Other	(550)	(46)
Net cash (used in) provided by investing activities	(443,792)	12,548
Cash flows from financing activities
Net increase (decrease) in deposits	143,646	(7,473)
Net decrease in short-term borrowings	(9,151)	(700)
Dividends paid	(30,700)
Distributions paid		(357,670)
Proceeds from employee stock purchase plan	528
Net cash provided by (used in) financing activities	104,323	(365,843)
Net decrease in cash and cash equivalents	(274,446)	(301,137)
Cash and cash equivalents at beginning of period	1,052,058	2,650,195
Cash and cash equivalents at end of period	777,612	2,349,058
Supplemental disclosures
Interest paid	7,457	6,452
Income taxes paid, net of income tax refunds	180	(7,794)
Noncash investing and financing activities:
Transfers from loans and leases to other real estate owned	524	202
Transfers from loans and leases to loans held for sale	$ 659
Derivative liability entered into in connection with sale of investment securities		$ 8,828