Note (17)—Commitments and contingencies:

Some financial instruments, such as loan commitments, credit lines, letters of credit, and overdraft protection, are issued to meet customer financing needs. These are agreements to provide credit or to support the credit of others, as long as conditions established in the contract are met, and usually have expiration dates.

Commitments may expire without being used. Off-balance sheet risk to credit loss exists up to the face amount of these instruments, although material losses are not anticipated. The same credit policies are used to make such commitments as are used for loans, including obtaining collateral at exercise of the commitment.

	Year Ended
	December 31,
	2017		2016
Commitments to extend credit, excluding interest rate lock commitments	$	977,276	$	579,879
Letters of credit		22,882		22,547
Balance at end of period	$	1,000,158	$	602,426

Commitments under non-cancelable operating leases were as follows, before considering renewal options that generally are present:

2018	$	3,533
2019		2,806
2020		2,318
2021		2,074
2022		1,623
Thereafter		5,350
Total	$	17,704

Rent expense for the years ended December 31, 2017, 2016 and 2015, was $4,245, $3,904 and $3,750, respectively.

In connection with the sale of mortgage loans to third party investors, the Bank makes usual and customary representations and warranties as to the propriety of its origination activities. Occasionally, the investors require the Bank to repurchase loans sold to them under the terms of the warranties. When this happens, the loans are recorded at fair value with a corresponding charge to a valuation reserve. The total principal amount of loans repurchased (or indemnified for) was $4,704 and $8,326 and $2,453 for the years ended December 31, 2017, 2016 and 2015, respectively. The Bank has established a reserve associated with loan repurchases. This reserve is recorded in accrued expenses and other liabilities on the consolidated balance sheet. The following table summarizes the activity in the repurchase reserve:

	For the year ended
	December 31,
	2017			2016			2015
Balance at beginning of period	$	2,659		$	2,156		$	828
Provision for loan repurchases or indemnifications		810			512			1,375
Recoveries on previous losses		—			9			—
Losses on loans repurchased or indemnified		(83	)		(18	)		(47	)
Balance at end of period	$	3,386		$	2,659		$	2,156