"shouldn't it be asking for the total on Dec 31, 2016?"
No. TurboTax does not calculate RMDs. TurboTax is asking for the 2017 year-end balance for one of two reasons: either you made an excess traditional IRA contribution and TurboTax needs to calculate the penalty on the lesser of the excess and the 2017 year-end balance, or you have basis in nondeductible traditional IRA contributions, made a distribution from a traditional IRA in 2017 and TurboTax needs to know the 2017 year-end balance to be able to calculate on Form 8606 the taxable and nontaxable amounts of the distribution.
Obtain the year-end value(s) of your traditional IRA(s) from your year-end statement(s).
"shouldn't it be asking for the total on Dec 31, 2016?"
No. TurboTax does not calculate RMDs. TurboTax is asking for the 2017 year-end balance for one of two reasons: either you made an excess traditional IRA contribution and TurboTax needs to calculate the penalty on the lesser of the excess and the 2017 year-end balance, or you have basis in nondeductible traditional IRA contributions, made a distribution from a traditional IRA in 2017 and TurboTax needs to know the 2017 year-end balance to be able to calculate on Form 8606 the taxable and nontaxable amounts of the distribution.
Obtain the year-end value(s) of your traditional IRA(s) from your year-end statement(s).