Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Financial Asset and Liabilities Measured at Fair Value on Recurring Basis

The Company has segregated all financial assets and liabilities that are measured at fair value on a recurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to estimate the fair value at the measurement date 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)	Level 1		Level 2		Level 3		Total
Assets
Securities available for sale	$	—	$	4,590,062	$	—	$	4,590,062
Mortgage loans held for sale	—		134,916		—		134,916
Derivative instruments	—		31,265		—		31,265
Total	$	—	$	4,756,243	$	—	$	4,756,243
Liabilities
Derivative instruments	$	—	$	25,154	$	—	$	25,154
Total	$	—	$	25,154	$	—	$	25,154
	December 31, 2016
	Level 1		Level 2		Level 3		Total
Assets
Securities available for sale	$	—	$	3,446,097	$	—	$	3,446,097
Mortgage loans held for sale	—		157,041		—		157,041
Derivative instruments	—		38,886		—		38,886
Total	$	—	$	3,642,024	$	—	$	3,642,024
Liabilities
Derivative instruments	$	—	$	30,209	$	—	$	30,209
Total	$	—	$	30,209	$	—	$	30,209

Gains and Losses Included in Earnings Related to Asset and Liabilities Measured at Fair Value on Recurring Basis

Gains and losses (realized and unrealized) included in earnings (or accumulated other comprehensive income) during 2017 related to assets and liabilities measured at fair value on a recurring basis are reported in non-interest income or other comprehensive income as follows:

(Dollars in thousands)	Non-interest income			Other comprehensive income (loss), net of tax
Total gains (losses) included in earnings	$	(1,166	)	$	—
Change in unrealized gains (losses) relating to assets still held at December 31, 2017	—			(11,721		)

Financial Asset and Liabilities Measured at Fair Value on Nonrecurring Basis

The Company has segregated all assets and liabilities that are measured at fair value on a non-recurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date in the tables below.

	December 31, 2017
(Dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets
Loans	$	—	$	—	$	71,210	$	71,210
OREO, net	—		—		3,029		3,029
Total	$	—	$	—	$	74,239	$	74,239
	December 31, 2016
(Dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets
Loans	$	—	$	—	$	93,485	$	93,485
OREO, net	—		—		185		185
Total	$	—	$	—	$	93,670	$	93,670

Summary of Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance for Mortgage Loans Held for Sale

The following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for mortgage loans held for sale measured at fair value:

	December 31, 2017						December 31, 2016
(Dollars in thousands)	Aggregate Fair Value		Aggregate Unpaid Principal		Aggregate Fair Value Less Unpaid Principal		Aggregate Fair Value		Aggregate Unpaid Principal		Aggregate Fair Value Less Unpaid Principal
Mortgage loans held for sale, at fair value	$	134,916	$	131,276	$	3,640	$	157,041	$	153,801	$	3,240