Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Estimated Fair Values and Carrying Amounts of Financial Instruments

The carrying amount and estimated fair values, as well as the level within the fair value hierarchy, of the Company’s financial instruments are included in the tables below. See Note 1, Summary of Significant Accounting Policies, for a description of how fair value measurements are determined.

	December 31, 2017
(Dollars in thousands)	Carrying  Amount		Fair Value		Level 1		Level 2		Level 3
Financial Assets
Cash and cash equivalents	$	625,724	$	625,724	$	625,724	$	—	$	—
Investment securities	4,817,380		4,818,026		—		4,818,026		—
Loans and loans held for sale, net of unearned income and allowance for loan losses	20,072,206		19,961,773		—		134,916		19,826,857
Derivative instruments	31,265		31,265		—		31,265		—
Financial Liabilities
Deposits	21,466,717		21,460,782		—		21,460,782		—
Short-term borrowings	991,297		991,297		516,297		475,000		—
Long-term debt	1,495,835		1,476,899		—		—		1,476,899
Derivative instruments	25,154		25,154		—		25,154		—
	December 31, 2016
(Dollars in thousands)	Carrying Amount		Fair Value		Level 1		Level 2		Level 3
Financial Assets
Cash and cash equivalents	$	1,362,126	$	1,362,126	$	1,362,126	$	—	$	—
Investment securities	3,535,313		3,536,029		—		3,536,029		—
Loans and loans held for sale, net of unearned income and allowance for loan losses	15,077,293		15,066,055		—		157,041		14,909,014
Derivative instruments	38,886		38,886		—		38,886		—
Financial Liabilities
Deposits	17,408,283		16,762,475		—		16,762,475		—
Short-term borrowings	509,136		509,136		334,136		175,000		—
Long-term debt	628,953		617,656		—		—		617,656
Derivative instruments	30,209		30,209		—		30,209		—