#Python 3, 162 characters

p=print
t=int(input())
d=4*'-'
s='  '
a='+\n'
r=(t-1)*s
p(r+' _|_|_\n'+r+'|     |')
for i in range(2,t+1):b=(t-i)*s;p(b+'+-'+i*d+a+b+'| '+i*2*s+'|')
p('+-'+t*d+a)

It's not very clever, but I've never done one of these before. (Edit: removed unnecessary parentheses; reduced by one more character)

Python 3, 162 characters

p=print
t=int(input())
d=4*'-'
s='  '
a='+\n'
r=(t-1)*s
p(r+' _|_|_\n'+r+'|     |')
for i in range(2,t+1):b=(t-i)*s;p(b+'+-'+i*d+a+b+'| '+i*2*s+'|')
p('+-'+t*d+a)

It's not very clever, but I've never done one of these before. (Edit: removed unnecessary parentheses; reduced by one more character)

#Python 3, 163 characters

p=print
t=int(input())
d='----'
s='  '
a='+\n'
r=(t-1)*s
p(r+' _|_|_\n'+r+'|     |')
for i in range(2,t+1):b=(t-i)*s;p(b+'+-'+i*d+a+b+'| '+i*2*s+'|')
p('+-'+t*d+a)

It's not very clever, but I've never done one of these before. (Edit: removed unnecessary parentheses)

#Python 3, 162 characters

p=print
t=int(input())
d=4*'-'
s='  '
a='+\n'
r=(t-1)*s
p(r+' _|_|_\n'+r+'|     |')
for i in range(2,t+1):b=(t-i)*s;p(b+'+-'+i*d+a+b+'| '+i*2*s+'|')
p('+-'+t*d+a)

It's not very clever, but I've never done one of these before. (Edit: removed unnecessary parentheses; reduced by one more character)

#Python 3, 167 characters

p=print
t=int(input())
d='----'
s='  '
a='+\n'
r=(t-1)*s
p(r+' _|_|_\n'+r+'|     |')
for i in range(2,t+1):b=(t-i)*s;p(b+'+-'+(i)*d+a+b+'| '+(i*2)*s+'|')
p('+-'+t*d+a)

It's not very clever, but I've never done one of these before.

#Python 3, 163 characters

p=print
t=int(input())
d='----'
s='  '
a='+\n'
r=(t-1)*s
p(r+' _|_|_\n'+r+'|     |')
for i in range(2,t+1):b=(t-i)*s;p(b+'+-'+i*d+a+b+'| '+i*2*s+'|')
p('+-'+t*d+a)

It's not very clever, but I've never done one of these before. (Edit: removed unnecessary parentheses)