1st Source Corporation (Parent Company Only) Financial Information (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income:
Rental income from subsidiaries	$ 22,302	$ 17,156	$ 16,229
Other	12,319	12,051	14,273
Expenses:
Interest on subordinated notes	4,220	4,220	4,220
Interest on long-term debt and mandatorily redeemable securities	1,970	2,108	1,733
Interest on commercial paper and other short-term borrowings	484	541	211
Other	6,976	7,521	7,440
Income before income taxes	88,563	84,443	83,943
Income tax benefit	(31,077)	(26,374)	(28,985)
Net income	57,486	58,069	54,958
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	54,634	60,895	42,000
Parent
Income:
Rental income from subsidiaries	2,342	2,314	2,165
Other	426	408	418
Investment securities and other investment (losses) gains	26	(370)	626
Total income	38,858	36,162	33,638
Expenses:
Interest on subordinated notes	4,220	4,220	4,220
Interest on long-term debt and mandatorily redeemable securities	1,375	1,475	999
Interest on commercial paper and other short-term borrowings	30	36	23
Rent expense	1,737	1,713	1,698
Other	351	2,553	639
Total expense	7,713	9,997	7,579
Income before income taxes	31,145	26,165	26,059
Income tax benefit	1,721	2,722	1,650
Income before equity in undistributed (distributed in excess of) income of subsidiaries	32,866	28,887	27,709
Equity in (distributed in excess of) undistributed income of subsidiaries	24,620	29,182	27,249
Net income	57,486	58,069	54,958
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	54,634	60,895	42,000
Parent | Bank subsidiaries
Income:
Dividends	36,064	33,810	30,429
Expenses:
Equity in (distributed in excess of) undistributed income of subsidiaries	24,289	28,891	26,995
Parent | Non-bank subsidiaries
Expenses:
Equity in (distributed in excess of) undistributed income of subsidiaries	$ 331	$ 291	$ 254